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Page Cooper, M. R. A revision of the ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a elassinicanonoLine Ormithischiay (Rublishedtiuned9Ss.) ers eee ee 281 GosLiner, T. M. The aeolid nudibranch family Aeolidiidae (Gastropoda, Opisthobranchia) from MmoOpicalsouuneneAuricas (kublishedunel9 85>) many eee eer 233 GRIFFITHS, R. J. Description of a new South African arminacean and the proposed re-instatement of the genus Atthila Bergh (Mollusca, Opisthobranchia). (Published June 1985.)... 269 KENNEDY, W. J. & KLINGER, H. C. Cretaceous faunas from Zululand and Natal, South Africa. The ammonite family Kossmaticeratdae Spath> 1922° (Publishedtiune 1985.) ey = aes esas ee 165 KENSLEY, B. The faunal deposits of a Late Pleistocene raised beach at Milnerton, Cape Province, SoOumpaunicas(aublishedvApnill985s)) 2 te 455s ye eee ee eee oe ltt KLINGER, H. C. see KENNEDY, W. J. Orson, Si L. Early Pliocene Procellariiformes (Aves) from Langebaanweg, south-western Cape BIOMiNcee SOUUNEAtICaa(eublishedrApmil 1985.) as... one ase ee] ane is coe 123 Otson, S. L. An early Pliocene marine avifauna from Duinefontein, Cape Province, South Africa. (LPUULDNS OSG! ZA OTT USCIS) ee aoe ere ern ene eR OE Oo ann Ae) ee esc) Gea 147 SCHOLTZ, A. The palynology of the upper lacustrine sediments of the Arnot Pipe, Banke, Namaqualand (rublishedtAvornllOSs:). 55.4545. 5e meen ore ee ie 1

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BULLOUGH, W. S. 1960. Practical invertebrate anatomy. 2nd ed. London: Macmillan.

FISCHER, P.—H. 1948. Données sur la résistance et de le vitalité des mollusques. J. Conch., Paris 88: 100-140.

FiscHER, P.-H., DuvAL, M. & Rarry, A. 1933. Etudes sur les échanges respiratoires des littorines. Archs Zool. exp. gén. 74: 627-634.

Konn, A. J. 1960a. Ecological notes on Conus (Mollusca: Gastropoda) in the Trincomalee region of Ceylon. Ann, Mag. nat. Hist. (13) 2: 309-320.

Konn, A. J. 19606. Spawning behaviour, egg masses and larval development in Conus from the Indian Ocean. Bull. Bingham oceanogr. Coll. 17 (4): 1-51.

THIELE, J. 1910. Mollusca: B. Polyplacophora, Gastropoda marina, Bivalvia. In: SCHULTZE, L. Zoologische und anthropologische Ergebnisse einer Forschungsreise im westlichen und zentralen Siid-Afrika 4: 269-270. Jena: Fischer. Denkschr. med.-naturw. Ges. Jena 16: 269-270.

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ANNALS OF THE SOUTH AFRICAN MUSEUM ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

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THE PALYNOLOGY OF THE UPPER LACUSTRINE SEDIMENTS OF THE ARNOT PIPE, BANKE, NAMAQUALAND

By A. SCHOLTZ

Cape Town Kaapstad

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THE PALYNOLOGY OF THE UPPER LACUSTRINE SEDIMENTS OF THE ARNOT PIPE, BANKE, NAMAQUALAND

By A. SCHOLTZ

Department of Archaeology, University of Stellenbosch (With 21 figures and 2 tables)

[MS accepted 7 December 1983]

ABSTRACT

The Arnot Pipe on the farm Banke, Namaqualand, is one of the most southerly in the Gamoep cluster of volcanics, which include ‘kimberlite’ and olivine-melilitite volcanic pipes. The upper sediments of this pipe, in which palynomorphs as well as plant macrofossils and vertebrate remains are found, are of lacustrine origin, having been laid down in a small, deep crater lake formed in a vent of a ‘kimberlite’ volcano. Radiometric dates from other pipes in. the. cluster indicate that the volcanic activity occurred between 64 and 71 Ma ago. In this study the systematic palynology of the top 20 m of polleniferous sediments is described.

Seventy-two forms of spores, conifer and angiosperm pollen are described and illustrated and 64 are formally classified. Fourteen new species and one new genus are defined and 21 further forms are, as far as is known, undescribed in previous literature. The possible affinity of the fossil forms to 28 plant families, including, amongst the angiosperms, the Proteaceae, Restionaceae, Ericaceae, Epacridaceae, Euphorbiaceae, Thymelaeaceae, Chloranthaceae, Casuarinaceae, Cornaceae, Caesalpinaceae and Anacardiaceae, are suggested. The relevance of these observations to hypotheses about the nature of Palaeogene vegetation in the African subcontinent are discussed. The Banke palynoflora is contrasted with those of a similar time range from tropical Africa and Australia to highlight what is unique about the combination of taxa present in an early Tertiary vegetation in southern Africa. Particular attention is paid to discussing the early history of some taxa that are at present characteristic elements of the Capensis Flora.

CONTENTS

PAGE

MITER OCU HOM ae aes eae toi nd CN pe Ny hen gat ale Lahn 2 The location and geology of the Arnot Pipe ................ 3 Previous studies of fossil material from the Arnot Pipe....... 7 DY AGIIN ES Mapp eee eh, cee eect ae ore hig No meetreen U8 ace net eas 9 Waterialtandumethodsieio ae, ane nmeege cides so en ere 10 Rr ANOL OD Weg rere is eA Ce ate See ela, echt ca boe aie eae eat 13 Species list and register of type specimenms.............. 14 IDESCHIPTOMS Aon A Rie y. oN eR ee areal aes Lette cg ae 7) OME Mi COUMES tvs syaeens nce eesti vet curt gtie eee le ees 88 DISCUSSION set epee eta ht he. eet flies oer ater « tee tare me tt tuegn al eee aw! 88 PNCKNOWICUSEMEMUSi te ie ot ee See e aa coed 103 NCTC TENCE Sr mibiar ney fe ential Rd hc: 5 MRS ky MAN ag ann leh einen 103

1

Ann, S. Afr. Mus. 95 (1), 1985: 1-109, 21 figs, 2 tables.

D ANNALS OF THE SOUTH AFRICAN MUSEUM

INTRODUCTION

This paper presents the first detailed account of an early Tertiary palynological assemblage from the subcontinent of southern Africa. To date, direct fossil evidence relating to late Cretaceous and Tertiary vegetation history and the evolution of plant groups in the region is very limited. The few relevant palynological studies are mentioned below.

Cursory studies have been published on the Arnot Pipe (Kirchheimer 1934), on the Knysna lignites—which may relate to a brief period in the Neogene (Thiergart et al. 1963)—and on a DSDP sequence of mid- to late Cretaceous marine sediments off the south-western Cape (McLachlan & Pieterse 1978). Morgan (1978), also studying DSDP material, described late Cretaceous assemblages from the Angola Basin. A brief study by Scholtz & Deacon (1982) of sediments from kimberlite pipes in Botswana has provided evidence for the rapid _ penetration of the ancient austral conifer forest by an early angiosperm flora during the mid- to late Cretaceous. Sah (1967) has published a detailed palynological study of the late Neogene sediments from Burundi, just south of the equator. Finally, Coetzee has done pioneering work on material from numerous short coastal sequences in the south-western Cape (Coetzee 1978a, 1981). This work will provide the first detailed palynological evidence about the nature of vegetation and history of vegetation changes during periods of the Neogene in this region.

There is, however, a long history of speculative thought on the subject of vegetation history and the evolution of certain families within the region, based on analysis of the botanical present (Levyns 1938, 1952, 1964; Adamson 1958; Taylor 1978; Goldblatt 1978). In the case of the more recent studies their evidence consists mainly of present patterns of biogeography viewed against the background of salient facts of plate tectonics. Much better use of the admittedly patchy African fossil evidence was made by Axelrod & Raven (1978), who combined fossil evidence, together with the two lines of evidence already mentioned, to produce their major work on the vegetation history of Africa. Since the fynbos vegetation of the Cape is a particularly striking component of the vegetation of southern Africa, being accorded the status of a plant kingdom on its own (Goldblatt 1978) and possessing a remarkable degree of endemism, and since the early history of a number of its characteristic taxa appears to be readily deducible from present patterns of distribution (Levyns 1964), many hypotheses have been advanced about its origin and evolution.

It was in this context of, on the one hand, an extremely limited fossil record and, on the other, much interest, many hypotheses and some knowledge of biogeographical and plant taxonomic patterns relevant to an historical perspec- tive, that a project to produce detailed palynological evidence on the composition of vegetation in the southern African subcontinent during earlier phases of history subsequent to the rise of the angiosperms to dominance of world floras was undertaken. The sediments of the Arnot Pipe were known to be of late Cretaceous to Eocene age (Estes 1977) and thus a restudy of this material was

PALYNOLOGY OF THE ARNOT PIPE 3

indicated. The importance of the Banke (Arnot) site had been emphasized by Goldblatt (1978: 416) and such references to the sketchy evidence previously available only increased the desirability of a thorough palynological study of the site.

A preliminary study revealed that careful processing could produce high pollen concentrations, that the palynomorphs were in a good state of preserva- tion, and that the pollen assemblage was much more diverse than Kirchheimer’s work (1934) had indicated.

As part of this project samples of lacustrine sediments were obtained from numerous other volcanic pipes in the Namaqualand region and from further afield, and in this paper reference is sometimes made to observations obtained in the process of ongoing work on this material.

The aim of this study has been to systematically describe the range of forms found in the top 20 m of polleniferous sediments (52—107 feet (c. 16-33 m) below surface) of the Arnot Pipe and to optimize the value of these descriptions for botanists and plant geographers by providing as many pointers to the natural affinities of the pollen forms as was possible. It must be noted that the latter aim was achieved almost exclusively by reference to the body of literature available to the author. This represents an essential aspect of research, but complementary aspects such as would be provided by the availability of a comprehensive pollen reference collection of the floras of the subcontinent or published regional pollen floras did not, in this study, enjoy their rightful place. The level of certainty with which affinities are suggested is therefore variable, but this should be clear from the text.

THE LOCATION AND GEOLOGY OF THE ARNOT PIPE

The Gamoep cluster of volcanic pipes associated with olivine-melilitite and related rocks (Moore 1979) is located in the north-western Cape about 80 km south of the Orange River and 100 km inland, and is centred around the hamlet of Gamoep (Fig. 1). The cluster contains upwards of 270 pipe-like bodies distributed with a north-north-easterly trend. It may be composed of a number of smaller clusters (Cornelissen & Verwoerd 1975). The cluster straddles the boundary between the Bushmanland plateau, at an elevation of around 1 200 m, and the highly dissected escarpment area of Namaqualand. The result is that on the plateau the pipes are typically buried under metres of sand and exposures are poor, while in dissected country the volcanic plugs, necks or sediment-filled depressions are exposed. The Arnot Pipe (30°22’S 18°26’E) on the farm Banke is one of the more southerly of the pipes in the cluster and is located in a zone of mildly dissected country between the plateau and the more highly dissected country of Namaqualand proper. Moore (1979) states that a second distinct cluster of pipes, associated as far as is known only with olivine-melilitite rocks, is found between the villages of Garies and Bitterfontein, 50 km south-west of the Gamoep cluster and closer to the coast.

4 ANNALS OF THE SOUTH AFRICAN MUSEUM

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dated occurrences (after Cornelissen & Verwoerd 1975; Moore 1979). Note: The majority of the more than 270 pipes in the Gamoep cluster are not shown.

PALYNOLOGY OF THE ARNOT PIPE 5

Rogers (1911), Reuning (1931), and Cornelissen & Verwoerd (1975) have described three categories of pipes that occur in the Gamoep cluster. Olivine- melilitite and olivine-nepheline-melilitite pipes often form conspicuous brown, domed hills in the dissected country. There are a limited number of occurrences where weathered ‘kimberlite’ or ‘pseudo-kimberlite’ is exposed at the surface, but the majority of occurrences consist of sediment and breccia-filled diatremes. These are mostly, if not always, underlain by ‘kimberlite’ and at the present surface display two modes of crater infilling. The minority are breccia fills in which the sediment is disturbed by numerous large and small blocks of country rock testifying to repeated explosive events. The majority are fills consisting of fine-grained weathered kimberlite, carbonaceous shales and mudstones deposited under lacustrine conditions. Doubt still remains about the exact mode or modes of eruption of these ‘kimberlites’, which in this cluster have produced relatively narrow pipes, some containing in the order of 300 m of bedded lacustrine sediment. Figure 2B is a geological section through one such sediment-filled pipe, Koppieskraal K5 (after Cornelissen & Verwoerd 1975).

The Arnot Pipe is an occurrence of the latter type. The diameter of the pipe is 280—325 m (Reuning 1931) and it is known to contain carbonaceous mudstones to a depth of at least 135 m (H. Jenner-Clarke, Aram Minerals, pers. comm.). During the early 1930s a prospecting pit located towards the middle of the pipe was sunk to a depth of 36 m to investigate the contents of the pipe (Fig. 2A). Ina paper concerning the composition and geochemistry of the lower section of sediments exposed in the excavation Reuning (1934) reached two conclusions of relevance to the present work. Firstly, the sediments of the Arnot Pipe consist of weathered ‘kimberlite’. This is an important point in suggesting the possible age of the pipe (see section on ‘dating’). Secondly, since the lower sediments of the pipe were composed of fine weathered and transported ‘kimberlite’ material with an almost complete absence of derivatives from the country rock, Reuning suggested that they were derived from the cone of a strato-type volcano that, within the catchment area, entirely blanketed the country rock (Namaqualand gneiss). In an earlier paper, however, Reuning (1931) had suggested another, or complementary, reason that could explain this phenomenon as well as the lack of heavier minerals such as ilmenite (derived from the ‘kimberlite’ itself) in the mudstones of the pipe. A flat landscape together with the luxuriant plant growth indicated by the rich fossiliferous nature of the sediments could have resulted in a general low efficiency of water transport and selective deposition of finer sediments towards the centre of the pipe. This suggestion is supported by the work of Hawthorne (1975), who confirms that at least in the larger sedimentary basins of the pipes found in the Botswana Kimberlite Province, coarser material is selectively concentrated around the margins of the pipes. In the same paper Hawthorne suggests that the actual volume of material ejected by these types of volcanoes may have been quite small and that the cones of ejectamenta would have been correspondingly low.

6 ANNALS OF THE SOUTH AFRICAN MUSEUM

main shaft

Be gneiss

mudstone

water table

sandstone layers - carbonaceous mudstone

dip 30-40 dip 55°

buff coloured fine grained “kKimberlitic’ sediments interbedded with carbonaceous mudstone. rich in macrofossils, frogs. leaves and branches fewer frogs, but richer accumulation of leaves

80 ft

arkose and grit

carbonaceous mudstone

conglomerate

tuffaceous “kimberlite”

"kimberlite’with blocks of Country rock

Fig. 2. A. A stratigraphic section of the known sequence of the Arnot Pipe. The upper 33 m (107 feet) (maximum depth of the 1929 excavation) at the main shaft and the side excavations are shown after Reuning (1931). (Reuning’s measurements are given in feet.) The provenance of samples examined in this study is indicated. The carbonaceous mudstones were recorded to a depth of 135m in drilling done by H. Jenner-Clarke (pers. comm.) during the 1960s. B. A stratigraphic section based on the logs of two cores of the Koppieskraal K5 pipe. This can be taken as a representative reconstruction of the stratigraphy of sediment-filled pipes in the Gamoep cluster (after Cornelissen & Verwoerd 1975).

PALYNOLOGY OF THE ARNOT PIPE 7

A final point in respect of the origin of the fine sediments of the pipe and the lack of coarser sediments needs to be made. In Reuning’s (1931, 1934) arguments he assumed that the substrate in the area at the time of deposition would have been the country rock, Namaqualand gneisses. However, inclusions of Dwyka shales have been observed in pipes (Moore 1979: 9) and in the present study an odd palynomorph specimen of Permian—Triassic provenance was observed. This indicates that at the time when sediments were being deposited in the crater lake some Dwyka cover was still present in the area.

From this survey of what is known of the geology of the pipes the following picture emerges of the local environment during the time of eruption and sedimentation of the pipes. A great many strato-type ‘kimberlite’ volcanoes erupted during a relatively short time in a small area. (Using an estimate of a total of at least 350 pipes in a region of 8 400 km? and the present span of radiometric dates of 7 Ma, the following calculations can be made: The average density of pipes is one per 24 km’, though they may be concentrated in subclusters with densities of about one per 4 km’; average time between eruptions 17 000 years.) Many small crater lakes could have been synchronously present in the region although, taking into account the ease with which the ejectamenta could have weathered, each crater may have had a relatively short life of sediment capture before infilling was completed.

Using the range of estimates of sedimentation rates for alluvial fan sediments given by Hooke (1968) and Beaty (1970) it would require between 300 000 and 4 000 000 years to accumulate the possible depth of sediment present in the Arnot Pipe (135-300 m). The rate of sedimentation, however, would decrease as the cone height and supply of tefra was reduced.

The basins would presumably have remained as swamp-like features for a longer period of time and, due to compaction or shrinkage of the initial sedimentary mass, may have retained a minor ability to capture sediments. The steeply inward-dipping strata often observed in the pipes (see Fig. 2) is evidence that this may have occurred. The small drainage basins feeding the lakes would have been largely unrelated to the developed drainage patterns of the region.

The general landscape was probably dominated by the small emergent cones of the ‘kimberlite’, strato-type volcanoes in various stages of erosion and, for the rest, there is little reason to suppose that a relatively flat, mature landscape did not exist (Mabbutt 1955). Although in the present the peaks of the nearby Kamiesberge rise some 150-200 m above the plateau, most of the present relief of Namaqualand is probably the result of more recent incision.

PREVIOUS STUDIES OF FOSSIL MATERIAL FROM THE ARNOT PIPE

During the 1930s, Reuning and later Boonstra selected samples of material from the dump of the main excavation. Boonstra (unpublished notes in the South African Museum) roughly indicated the stratigraphic provenance of a series of

8 ANNALS OF THE SOUTH AFRICAN MUSEUM

TABLE 1

Material from the 1929 excavation of the Arnot Pipe collected and provenanced by E. Reuning and L. D. Boonstra and analysed in this study.

Provenance of sample Description of the material

52-58 feet (16-18 m) Bituminous, carbonaceous mudstone.

Unprovenanced Bituminous, carbonaceous mudstone.

65-70 feet (20-21 m) Buff-coloured finely laminated mudstone.

70-90 feet (21-27 m) Buff to grey-coloured mudstone.

90-100 feet (27-30 m) Buff-coloured mudstone with fine silty laminations.

100-107 feet (30-33 m) Buff-coloured mudstone.

100-107 feet (30-33 m) Brown-coloured mudstone with large flecks of organic material.

five small samples (see Fig. 2A and Table 1). A considerable amount of material was deposited at the South African Museum and the following categories of fossil material were later studied by various researchers: leaves (Rennie 1931), wood (Adamson 1931), frogs (Haughton 1931), and palynomorphs (Kirchheimer 1934).

The fossil leaf collection consisted of 70 fragments of dicotyledonous leaves (and a single fern frond) and Rennie recognized at least twelve different types. In his short paper only six forms are illustrated by rough line-drawings. The most common form was described as strap-shaped with serrate margins, and although Rennie did not do so, it could be described as sclerophyllous. This form was tentatively compared to the leaves of Myrica, the comparison to some extent being based on identifications contained in the work of Berry (1925) on Upper Cretaceous leaf assemblages from North America (Rennie 1931: 252). Rennie’s tentative comparison is rendered less likely by Chourey’s (1974: 131, 145) thorough criticism of Berry’s work. Chourey noted that in the early years of study of leaf fossils of late Cretaceous—Tertiary age, inadequate identification criteria were employed and many identifications made then can no longer be accepted. In ~ particular many fossils were identified either as myricaceous or proteaceous; affinity with the genus Banksia of the Proteaceae was regularly suggested. In fact this tentative alternative identification was made by Berry in the very paper cited by Rennie. It should be noted that, while rejecting most of the Myrica identifi- cations made on late Cretaceous—early Tertiary material from North America and Europe, Chourey (1974) suggests that the phenomenon of a world-wide occurrence and prominence of this form type is significant and worthy of further study. The ‘myricaceous’ leaves from Arnot are part of this world-wide phenomenon.

It was not possible to obtain adequate descriptions of the remaining eleven leaf types to allow for identification and Rennie merely noted their general ‘mesophytic’ habit.

Adamson (1931) studied silicified wood samples from opalized sections of the superficial sandstone layers found close to the contact between the pipe fill and the gneiss. He identified the fossil wood as that of Ficus cordata, which grows in the area at present. Kirchheimer (1934: 47) quotes Reuning’s statement that these sandstone layers may be of a substantially younger age than the underlying clays.

PALYNOLOGY OF THE ARNOT PIPE 9

Haughton (1931), in the most detailed of these early studies, described a single new species of Pipidae, Eoxenopoides reuningii and, in terms of relatively conservative pipid evolution and lacunae in their fossil record, could only assign a Cretaceous to early Tertiary age to the form. Estes (1977) agreed with Haughton’s systematic description and on morphological grounds also upheld Haughton’s age bracketing. However, on extraneous grounds he favoured an Oligocene age for the sediments (Estes 1977: 51).

Kirchheimer (1934) cursorily described six palynomorph types including two disaccate and four triaperturate angiospermous forms. He also mentioned that spores and inaperturate grains had been observed. He obtained his best results from thin sectioning of opal concretions and obviously encountered difficulties in processing the carbonaceous clays of the lower layers available to him.

DATING

The best biostratigraphic evidence on which to base an age estimate for the sediments of the Arnot Pipe has been produced by the present study and is discussed in a later section in the context of the radiometric evidence mentioned below. The suggestion by Axelrod & Raven (1978), based on an extremely tenuous comparison with the North American and Mediterranean plant macro- fossil record, that the occurrence of a sclerophyllous leaf type indicates a late Eocene to Miocene age, can be regarded as insubstantial. The arguments advanced by Reuning (1931) and Haughton (1931) on sedimentological and geomorphological grounds for a late Cretaceous age were probably never intended to be more than speculative.

The most positive dating evidence relevant to suggesting a possible age for the Arnot sediments consists of a number of radiometric determinations on material from pipes in the Gamoep cluster (Davis 1977). The dates and location of pipes are given in Figure 1. All the dates were obtained by the *°U/*"°Pb method applied to zircon inclusions in kimberlitic material. Until these dates were available, the single K/Ar date of 38,5 Ma from an olivine-melilitite pipe on the farm Dikdoorn in the Garies—Bitterfontein cluster was the most pertinent radiometric determination relevant to the possible age of the Gamoep cluster. This was also the only date available when the dating of the Arnot sediments was last discussed (Estes 1977).

In view of the range of dates presently available, the evidence is strongly in favour of accepting a 60-70 Ma age bracket for volcanic activity in the Gamoep cluster and for the Arnot Pipe. Firstly, all three pipes dated in the Gamoep cluster are apparently ‘kimberlitic’, as is the Arnot Pipe. Secondly, the five dates available are relatively tightly grouped within a 7 Ma time span and the Arnot Pipe is within 30 km of the dated pipes. No olivine-melilitite pipes from the area have yet been dated.

Two K/Ar dates from olivine-melilitite pipes in the small cluster south of Garies are available and are younger or considerably younger than the dates for

10 ANNALS OF THE SOUTH AFRICAN MUSEUM

the main Gamoep cluster, i.e. 54,1 and 38,5 Ma. It must be pointed out that the younger date here and the other two Oligocene dates shown in Figure 1 have in fact not been fully published (Kréner 1973) and should be treated with caution. In contrast to the use of the *°U/*%°Pb method to date the pipes in the Gamoep cluster, the K/Ar method was used in the case of the Garies—Bitterfontein pipes. Excluding possible problems involved in the dating techniques, the spread of dates from the Garies—Bitterfontein pipes as well as from olivine-melilitite pipes wider afield (see Fig. 1) may indicate that the time span of volcanic activity either in this small cluster or throughout the distribution of olivine-melilitites was much greater than that of the volcanic activity associated with the ‘kimberlite’ pipes of the Gamoep cluster. Moore (1979) (see below) has suggested at least two mechanisms that could explain the phasing of volcanic activity resulting in extrusion of lighter ‘kimberlite’ earlier than that of more dense olivine-melilitite. He (1979: 136) also discusses some disparities in results obtained in the radiometric dating of kimberlites, olivine-melilitites and related rocks, and suggests that many determinations are possibly questionable.

Moore (1973, 1979) develops hypotheses that might explain:

(a) the possible younger ages of the olivine-melilitite versus the ‘kimberlite’ volcanics of the region;

(6) the possible pattern of younger dates occurring closer to the coast; and

(c) the possible concomitant pattern of progressive increase in the magnesium oxide content of volcanics from the olivine-melilitites of the Garies—

Bitterfontein cluster through those of the Gamoep cluster to the ‘kimberlites’

of the latter region.

These hypotheses involve the late Cretaceous—Oligocene epeirogenic uplift along the warp axis of the western escarpment as a primary cause of volcanic activity. Furthermore, either the fractionation of the parent magma in the stress zone beneath the warp and a resultant enrichment of a less dense portion with volatiles could lead to a first phase of volcanic activity in which ‘kimberlite’ was extruded, or the progressive thickening of the craton towards the interior of the continent might cause extrusion of magmas from different depths and thus explain the coast—interior gradient of geochemical attributes and perhaps dates.

So much for the possible dating of the volcanics that provides a maximum age for the lacustrine deposits. As suggested it is likely that infilling of the craters would have proceeded relatively rapidly, or would at least at first have been rapid. The estimates obtained from sedimentological work in similar environ- ments suggest that a maximum of 4 Ma could have been required to accumulate the depth of deposit that may be present in the Arnot Pipe.

MATERIAL AND METHODS

As already stated, the material curated in the South African Museum was collected by E. Reuning and L. D. Boonstra during the 1930s. Even the five small samples whose stratigraphic provenance was indicated by Boonstra (see Fig. 2A

PALYNOLOGY OF THE ARNOT PIPE 1]

and Table 1) were probably collected from the dump (which was presumably to some extent systematically organized) after the excavation had been closed. This is inferred from the fact that this small series includes samples from the lowest levels reached in the excavation, yet the work had ceased at this level (35 m) due to the instreaming of water, and the pit would presumably have filled with water to the level of the water-table 20 m higher up. The coherent pattern of the pollen diagram (Fig. 3) does to some extent suggest that the provenancing of the samples is correct.

The seven samples studied are listed and described in Table 1, in the same sequence as their pollen spectra appear in the pollen diagram.

The bulk of the collection was unprovenanced, but since this material often contains macroscopic fossil material, it is unlikely to have come from the upper third of the excavation. Reuning (1931) noted that preservation of fossil material above the level of the water-table was poor. On the other hand, in view of the pollen counts (Fig. 3), it seems unlikely that the bulk of the samples could have come from below the 18 m (60 foot) level. The combined count of two counts on the unprovenanced material is placed below those of Boonstra’s 52-58 foot (16-18 m) samples on the pollen diagram and are virtually indistinguishable from the latter.

The unprovenanced material is of two sedimentological types—a dark, carbonaceous mudstone and a buff-coloured mudstone. The pollen spectra from the two types are similar and unfortunately, since the best-preserved and richest concentrations were obtained from this material, many holotypes designated in this study are located in preparations from it.

It appeared that two sediment types also occurred between 30 and 33 m (100-107 feet), but no indication was given about their stratigraphic relationship. In Table 1 and Figure 3, the spectrum from the buff-coloured mudstone 1s arbitrarily placed above that of the dark, carbonaceous mudstone.

Kirchheimer used a single-stage process, cold hydrofluoric acid digestion, to concentrate palynomorphs. The stratigraphic provenancing of his samples was uncertain. In the present study a six-stage process was employed, consisting of the following steps:

1. Crushing and dispersal of the sample in a 0,3M solution of tetrasodium pyrophosphate, followed by numerous short centrifuges and rinses in deionized water to wash out the fine clay fraction. If necessary, additional applications of tetrasodium pyrophosphate solution were used. This treatment is an adaptation of the process described by Bates et al. (1978) but was independently suggested by a soil scientist, J. J. N. Lambrechts of the Department of Agriculture, University of Stellenbosch.

2. Standard zinc chloride heavy-liquid flotation to separate organic and larger-sized inorganic fractions.

3. In the treatment of a few of the more heavily carbonaceous samples it was necessary to cause some oxidation using either 30 per cent hydrogen peroxide solution or nitric acid.

[2 ANNALS OF THE SOUTH AFRICAN MUSEUM

eS 3s ¢ & SSeS a ee Ss , 1 = © es ) w o co a 8 4! > ~ as" 38 Ss 2 8 4 via: eo en tee PROVENANCE OF SAMPLE — ~ . - —_- = oe o Qo mm [.s} PS = — a — a = ] e - =< e@ = = = = = oO = = oO = = STEREISPORITES TRIORITES OPERCULATUS OTHER SPORES | J DICOLPOPOLLIS TRICOLPITES RETICULATUS CLAVATIPOLLENITES TRIORITES SPHERICUS PROPYLIPOLLIS ERICIPITES PODOCARPIDITES NILFOROIA “ LE he 8 ARAUCARIACITES Pd ™m TRICOLPOROPOLLNITES ARNOTIENSIS uw cy [=] se E a R i R ry Wm TRICOLPOROPOLLENITES BRINKIAE S233 S & S EB poruen sun GT OW TM ™ rerpororerravires spuerrcus

Fig. 3. Pollen diagram showing relative abundance of those taxa that constitute greater than 1 per cent of the grains present at Arnot.

PALYNOLOGY OF THE ARNOT PIPE 1

4. Standard acetolysis process.

5. A two or three-minute rinse in hydrofluoric acid to destroy any remaining silica particles.

6. A rinse in warm 10 per cent hydrochloric acid.

After final washing with deionized water the concentrates were suspended in a 50 per cent glycerol solution for light microscopy or left in deionized water for mounting on SEM stubs. Permanent slides were made with glycerine jelly and sealed with nail varnish.

The full series of slides with holotypes and paratypes ringed and documented is deposited in the South African Museum. A register of South African Museum catalogue numbers for these holotypes and paratypes is given in the species list (e.g. SAM-K6155). A duplicate set of slides and the sealed phials containing the remaining concentrates is deposited in the Department of Archaeology, University of Stellenbosch. Counting of samples and photomicroscopy was done on a Wild M11, and SEM work was done on a JEOL JSM-35 housed in the Department of Physics, University of Stellenbosch.

PALYNOLOGY

Kemp & Harris (1977: 5) provide a recent review of the problems encountered in the systematic palynology of early Tertiary material. They state that “Tertiary palynology even more than the palynology of older sedimentary rocks, has suffered from a marked ambiguity of approach’. This ambiguity of approach arises in that three different approaches to nomenclature have been applied. Authors have variously assigned fossil palynomorphs to extant genera, used a name that suggests affinity to an extant genus (e.g. Araucariacites for forms resembling pollen of the genus Araucaria), or applied an artificial name based on morphological criteria alone (e.g. Triorites or Monocolpopollenites).

In addition, a certain regionality of nomenclature, reflecting the isolation in which early palynological work was done, is inherited by present-day palynol- ogists (depending on what literature they are exposed to). This problem can be compounded by the difficulties entailed in keeping up to date with more recent work published in an array of journals.

Most palynologists working on early Tertiary material have elected, firstly, to continue to use the binomial system of nomenclature together with the standard botanical rules of typification, priority, etc. This promotes stability and some measure of uniformity in the use and creation of names for fossil palynomorphs, and is the system adhered to in the present study. However, it does not discourage the proliferations of names and the growth of ‘portmanteau’ genera. Secondly, in establishing new genera palynologists have favoured the artificial system of nomenclature, which promotes the utilization of palynology as a strati- graphic tool (Sah 1967: 6), and this practice is also followed in the present work.

In this study the descriptive and stratigraphic palynological literature from Australia, India and tropical Africa has been most often consulted. As could be

14 ANNALS OF THE SOUTH AFRICAN MUSEUM

expected, in view of its isolation from these areas, the palynomorph assemblage from Banke appeared unusual and many new specific names have resulted. Both in the occurrence of a number of unique forms and in the general composition of the assemblage, the already developed distinctiveness of the flora of the subcontinent is apparent.

A new specific or generic name was not proposed unless the form concerned was reasonably common in the Arnot samples. A large number of forms were present at low frequencies and in these cases, if at least three specimens in good state of preservation were observed, the forms were described and illustrated, placed if possible in a genus, and their affinities suggested. This was deemed to be worthwhile in terms of the aims of the study and the unique nature of these observations at present. Other forms will no doubt be systematically described as work on the pollen and spore assemblages from ‘“kimberlite’ pipe occurrences in the northern Cape and Botswana is extended. Sequences are already known in which elements rare at Arnot are common or even dominant. One form, referred to informally as Fenestriorites, is not described in the present paper as it is being described elsewhere. The form promises to be an especially important marker species in the regional sequence. Some importance is therefore placed on its occurrences in the lowest levels as yet sampled at Arnot (where it is extremely rare) and this is discussed in the section on interpretation of the present palynological evidence.

SPECIES LIST AND REGISTER OF TYPE SPECIMENS Spores

Trilete spores Stereisporites sp. Cyathidites australis Couper, 1953 Planisporites sp. Foveotriletes margaritae (van der Hammen) Germeraad et al., 1968 Foveotriletes lacunosus Partridge, in Stover & Partridge, 1973 Foraminisporis sp. Herkosporites elliottii Stover, in Stover & Partridge, 1973 Camarazonosporites bankiensis sp. nov. Holotype SAM-K6155 Polypodiaceoisporites sp. Trilites sp.

Monolete spores Microfoveolatosporis fromensis (Cookson) Harris, 1965 Cicatricososporites sp.

Alete spores Reticulatasporites grandis sp. nov. Holotype SAM-K6156; paratypes SAM-—K6157, K6158

PALEY NOLOGY OFSHHE ARNOT PIPE

Spores not assigned to genus Forma A Forma B Forma C Forma D

Pollen of Coniferae

Inaperturate pollen Araucariacites australis Cookson ex Couper, 1953 Araucariacites sp.

Monosaccate pollen Zonalapollenites sp. A Zonalapollenites sp. B

Disaccate pollen Lygistepollenites sp. Podocarpidites sp. Podocarpidites kamiesbergensis sp. nov. Holotype SAM-K6159; paratypes SAM—K6160, K6161, K6162 Podocarpidites riembreekensis sp. nov. Holotype SAM-K6163; paratypes SAM-—K6164, K6165, K6166

Pollen of Angiospermae

Monoaperturate pollen

—Monocolpate pollen Arecipites plectilimuratus Chmura, 1973 Arecipites sp. A

Arecipites sp. B Liliacidites sp. A Liliacidites sp. B Clavatipollenites sp. A Clavatipollenites sp. B Clavatipollenites sp. C Monocolpopollenites sp. A Monocolpopollenites sp. B

—Monoporate pollen

Milfordia hypolaenoides Erdtman, 1960 Milfordia sp.

—Dicolpate pollen

Dicolpopollis sp.

—Monocolpate pollen not assigned to genus Forma E

16 ANNALS OF THE SOUTH AFRICAN MUSEUM

Triaperturate pollen

—Triporate pollen Triorites operculatus sp. nov.

Holotype SAM-—K6167; paratypes SAM—K6168, K6169, K6170 Triorites sphericus sp. nov.

Holotype SAM-K6171; paratypes SAM—K6172, K6173 Triorites harrisii Couper, 1960 Triporopollenites namaquensis sp. nov.

Holotype SAM-—K6175; paratypes SAM-—K6176, K6177, K6178 Proteacidites sp. A Proteacidites sp. B Propylipollis meyeri sp. nov.

Holotype SAM-K6179; paratypes SAM-—K6180, K6181, K6204 Propylipollis sp. Fenestriorites sp. (not described in this paper)

—Tricolpate pollen

Tricolpites reticulatus Cookson, 1947 Tricolpites sp. A Tricolpites sp. B Tricolpites sp. C Tricolpites sp. D Crototricolpites densus Salard-Cheboldaeff, 1978 Spinitricolpites jennerclarkei gen. et sp. nov. Holotype SAM-K6182; paratypes SAM—K6183, K6184, K6185

—Tricolporate pollen

Tricolporopollenites grandis sp. nov.

Holotype SAM-K6186; paratypes SAM-K6187, K6188 Tricolporopollenites arnotiensis sp. nov.

Holotype SAM-K6189; paratypes SAM—K6190, K6191 Tricolporopollenites brinkiae sp. nov.

Holotype SAM-K6193; paratypes SAM—K6194, K6195 Tricolporopollenites coetzeeae sp. nov.

Holotype SAM-K6196; paratypes SAM-K6192, K6174 Tricolporopollenites sp. A Tricolporopollenites sp. B Tricolporopollenites spp. C & D

Pollen with more than three apertures

Retistephanocolpites sp. Grootipollis reuningli sp. nov.

Holotype SAM-K6197; paratypes SAM-—K6202, K6203 Ulmipollenites sp.

PALYNOLOGY OF THE ARNOT PIPE 17

Inaperturate pollen Crotonipollis burdwanensis Baksi, Deb & Siddhanta, 1979

Pollen found in obligate tetrads Ericipites sp. A Ericipites sp. B Dicotetradites sp. Triporotetradites sphericus sp. nov. Holotype SAM-—K6198; paratypes SAM-—K6199, K6200, K6201

Dicotyledononous pollens not assigned to genus Forma F Forma G Forma H Forma I

DESCRIPTIONS Spores

‘The identification of Tertiary spores is more problematical than that of fossil pollen grains. This is partly because they are less well known but mainly because, as Knox (1935) and Selling (1946) have shown, a particular type is not necessarily restricted to a single genus or even family and considerable variation often exists within a genus’— Cookson (1947: 135).

Trilete spores Genus Stereisporites Pflug, in Thomson & Pflug, 1953

For a discussion of this genus see Dettmann (1963: 25).

Stereisporites sp. Fig. 4A—D Compare

Sphagnum antiquasporites Wilson & Webster, 1946: 273 (fig. 2).

Triletes australis Cookson, 1947: 136, pl. 15 (figs 58-59).

Sphagnites australis (Cookson) Balme, 1957: 15, pl. 1 (figs 1-3).

Stereisporites antiquasporites (Wilson & Webster) Dettmann, 1963: 25, figs 20-21. Harris 1974: 79, pl. 24 (fig. 20).

Description

Microspore trilete, biconvex, amb subtriangular to subspherical with convex sides and broadly rounded angles. Laesurae straight and simple, length one-half spore radius. The exine is uniformly thick and the distal and probably the proximal surfaces are covered by very low angular rugulae. Equatorial diameter 24-35 pw, exine 1-2 wm.

18

ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 4. A-D. Stereisporites sp. EE. Cyathidites australis. _F—G. Planisporites sp. H. Foveotriletes margaritae. \—J. Foveotriletes lacunosus. K—L. Foraminisporis sp.

PALYNOLOGY OF THE ARNOT PIPE 19

Remarks

The slight thickenings in the radial regions at the equator and the low, distal polar thickening, circular in outline, mentioned by Dettman (1963: 25) were not observed, nor do they appear in either the descriptions or photomicrographs of Wilson & Webster (1946), Cookson (1947), Balme (1957) or Harris (1974). The differences between the present form and the species Stereisporites antiqua- sporites (Wilson & Webster) Dettmann, 1963, are therefore slight, but sufficient to prevent identification.

Affinity

The genus Sphagnites Cookson, 1953, was established to include fossil spores resembling those of the peat-moss family Sphagnaceae. (See discussion of Stereisporites in Boros & Jarai-Komlddi 1975: 9.)

Distribution

The genus is known from Jurassic to Tertiary sediments and is sometimes common in Australian late Cretaceous sediments, particularly in highly carbon- aceous samples (Dettmann 1963). Stereisporites sp. is the most common spore at Banke. Due to the long time range shown by the genus Stereisporites, it may have little stratigraphic value, but Balme (1957: 15) remarks that it is rarely seen in marine and transitional sediments and may therefore be important in facies studies. A Sphagnites form is illustrated but not described from the Knysna lignites (Neogene?) by Thiergart et al. (1963, table 2, fig. 6) and was also recorded in sediments of middle to late Cretaceous age off the south-western Cape (McLachlan & Pieterse 1978). A survey of the literature suggests that Sphagnites forms are not known from late Cretaceous or Tertiary sediments of tropical Africa. The modern family is strongly circumboreal in distribution, although one form is cosmopolitan and other forms occur in the Southern Hemisphere, mainly in New Zealand (Boros & Jarai-Komlddi 1975). A few Sphagnum species are found in southern Africa and are common although ‘confined to shaded mountain seeps, streambanks or swampy areas’ (Magill 1981: 23).

Genus Cyathidites Couper, 1953 See discussion in Dettmann (1963: 22).

Cyathidites australis Couper, 1953

Fig. 4E Cyathidites australis Couper, 1953: 27, pl. 2 (fig. 11).

Description

The spores are trilete. The laesurae are ciearly defined (about two-thirds of the radius of the spore), narrow and straight. The ends of the laesurae may

20 ANNALS OF THE SOUTH AFRICAN MUSEUM

terminate in a short bifurcation. The spores are triangular with rounded apices and the sides are mostly concave in polar view. The exine is thin and psilate, and both proximal and distal surfaces are convexly curved. Equatorial diameter 46-60 pw, exine 1 p.

Affinity

Couper (1953: 27), having compared the present form to the spores of the extant fern Thyrsopteris elegans, quoted Copeland (1947: 48) on the latter species: ‘It may well be a relict from the time when Dicksonia and Cyathea had a common ancestor.’ On the basis of the available evidence Couper suggested that Cyathidites australis may be the spore of a tree-fern.

Distribution

Cyathidites australis is widely distributed in the Mesozoic and Tertiary of the Northern Hemisphere and Australia, and is often abundant. It is a rare component of the Banke spore flora. Similar forms are present in the late Cretaceous (McLachlan & Pieterse 1978, pl. 1 (figs 1-2)) and Neogene (?) (Thiergart et al. 1963, pl. 2 (figs 12, 14—15)) of the southern African subcontinent.

Genus Planisporites Knox, 1950 Planisporites sp. Fig. 4F-—G

Description

The spore is trilete and its amb is subtriangular to deltoid with rounded corners. The exine is relatively thick. The distal face and equatorial regions are decorated with microconi, which are mostly solitary, but may also be arranged in rows. The bases of adjacent coni may be linked by fine ridges. The proximal face is psilate and the laesurae are long, thin and simple and almost reach the equator. The equatorial diameter of the illustrated specimen is 33 w and the exine is 2 wu thick.

Affinity There is no information regarding possible affinities of Planisporites sp.

Distribution

Planisporites sp. is rare at Arnot. There is no further information on the distribution of the genus.

PALYNOLOGY OF THE ARNOT PIPE 2A

Genus Foveotriletes Potonié, 1956 Foveotriletes margaritae (van der Hammen) Germeraad et al., 1968 Fig 4H

Triletes margaritae van der Hammen, 1954: 102, pl. 17. Foveotriletes margaritae (van der Hammen) Germeraad et al., 1968: 286, pl. 1 (figs 1-2).

Description

The spore is trilete with a roundly triangular amb and is circular to biconvex in lateral view. The laesurae are straight with finely serrate margins and are one- half the spore radius. The exine is relatively thin and the whole surface is densely covered by scrobuli; approximately sixty scrobuli per 100 «*. Equatorial diameter is 55 w; laesurae 15-18 w; exine 1-2 wp.

Affinity

Spores that resemble F. margaritae are produced by members of the Ophioglossaceae, especially the genera Botrychium and Ophioglossum (Salard- Cheboldaeff 1981).

Distribution

Foveotriletes margaritae is recorded from sediments of Palaeocene age in tropical Africa and South America, where it becomes extinct during the lower Eocene (Germeraad ef al. 1968). It is rare at Arnot.

Foveotriletes lacunosus Partridge, in Stover & Partridge, 1973 Fig. 4I-J Foveotriletes lacunosus Partridge, in Stover & Partridge, 1973: 248, pl. 14 (fig. 6).

Description

The spore is trilete and the amb is rounded triangular to subcircular. The distal surface is convex and the proximal is pyramidal. The laesurae are two-thirds to three-quarters spore radius, irregular, not straight, and have thin, steep lips. The proximal surface is psilate, the distal surface is covered with poorly delimited, shallow foveola that almost encroach on to the proximal face. The exine is relatively thick, approximately 2 uw, and its inner surface appears to follow the undulations of its outer surface. Equatorial diameter 35-37 wp.

Affinity There is no information on the affinity of F. lacunosus.

Distribution

Foveotriletes lacunosus is known from the Oligocene to Miocene in Australia; it is rare at Arnot.

22 ANNALS OF THE SOUTH AFRICAN MUSEUM

Genus Foraminisporis Krutzsch, 1959

See discussion in Dettmann (1963: 71).

Foraminisporis sp. Fig. 4K—L Compare Foraminisporis dailyi Dettmann, 1963: 72, pl. 14 (figs 15-18).

Description

The spore is trilete. The amb is rounded triangular to subcircular with a notch in what is probably a narrow sculptured cingulum (see Dettman 1963: 71) where the laesurae meet the equator. The outline of the grain is irregular. The laesurae are straight and placed on sculptured ridges running the length of the radial areas. The distal face is covered by verrucate to spinulate structures whose bases sometimes coalesce. The proximal face is distinctly less verrucate with occasional foveola. Equatorial diameter 45-50 p, cingulum 3 wp.

Affinity The affinity of the genus Foraminisporis is perhaps with the bryophyte family Anthocerotaceae (Dettmann 1963: 71).

Distribution

Foraminisporis 1s world-wide in the Cretaceous; F. dailyi is present in late _ Cretaceous sediments off the south-western Cape (McLachlan & Pieterse 1978). Foraminisporis sp. was common at Arnot.

Genus Herkosporites Stover, in Stover & Partridge, 1973 See discussion in Stover & Partridge (1973: 248).

Herkosporites elliottii Stover, in Stover & Partridge, 1973 Fig. 5A—B Herkosporites elliottii Stover, in Stover & Partridge, 1973: 248, pl. 13 (fig. 7).

Description

The spore is trilete, the amb roundly triangular and the laesurae extend almost to the equatorial margins. The radial area immediately bordering the lips of the laesurae appears smooth, but in the remainder of the radial region regularly spaced, thin structures (? folds) arranged at right angles to the laesurae are present. The proximal interradial area is psilate. The laesurae are narrow with thin raised lips. The distal surface is spinate; spines are of a uniform height 3-4 yu with abruptly broadening bases, which sometimes coalesce in fine ridges; space between spines 1,5—2,5 uw, exine 1 w, equatorial diameter 40-45 w.

PALYNOLOGY OF THE ARNOT PIPE 23

Affinity

There is no direct information on the affinities of Herkosporites. Dettmann (1963: 36) quotes Cookson & Dettmann (1958) on a comparison between the morphologically related genus Ceratosporites and certain members of the extant genus Selaginella.

9046

Fig. 5. A-B. Herkosporites elliottii. C-D. Camarazonosporites bankiensis sp. nov. E-F. Polypodiaceoisporites sp.

24 ANNALS OF THE SOUTH AFRICAN MUSEUM

Distribution

Herkosporites elliottii is distributed in the Palaeocene to Miocene in Australia; it was rare at Arnot.

Genus Camarazonosporites Pant ex Potonié, 1956 Camarazonosporites bankiensis sp. nov. Fig. SC-D

Etymology

This species is named after the farm Banke, near Platbakkies, Namaqualand, and the site name.

Description

The spores are trilete and cingulate with a convexly triangular amb and rounded apices; biconvex in lateral view. The proximal face is subpsilate, probably finely granulate. The distal face is covered by a fine hamulate sculpturing, which is completely lost in the radial equatorial region, following the characteristic trend for the reduction of the exine of this region in the genus Camarazonosporites. The narrow laesurae extend to the equator and are bordered by thin, steep membraneous folds, which thus form irregular lips. The lips may overfold the laesurae. The cingulum (equatorial crassitude) is 6-7 pu wide in the interradial regions, and narrows to 1-1,5 w in the radial region, giving the grain a rounded triangular aspect in plan view. Equatorial diameter is 59-63 p.

Remarks

Camarazonosporites bankiensis is quite common in the Banke material and can therefore serve as a type population. The spores are twice the size of the type species of the genus, and much larger than any other known species of Camarazonosporites. It is also larger than most species in morphologically related genera such as Coronatispora, Sestrosporites and Camarazonotriletes.

Affinity The affinities of C. bankiensis are not known. It has a general similarity to the spores of some members of the Lycopodiaceae.

Distribution

Camarazonosporites bankiensis is common at Arnot. The genus is known from the late Cretaceous. An apparently similar form, labelled Lycopodium- type, is present in the Knysna lignites (Neogene?) (Thiergart ef al. 1963, pl. 2 (figs 1—3)) but no description is provided.

PAL Y NOLOGY OPMHE ARNOT PIPE 25

Genus Polypodiaceoisporites Potonié, 1951 ex Potonié, 1956 Polypodiaceoisporites sp. Fig. SE-F

Description

A trilete, cingulate spore. The amb is triangular with broadly rounded apices. The laesurae are straight and reach the cingulum without extending into it. A concavely triangular area in the central radial area of the proximal face is markedly depressed below a surrounding ridge, which is decorated with robust rugulate structures. This sculpturing becomes reduced as the laesurae are approached within the centrally depressed area. The rugulate sculpturing on the distal face is formed by much flatter and broader structures. The cingulum is smooth and of variable width. Equatorial diameter 80 w, cingulum 6 w wide.

Affinity The generic designation suggests affinity to the Polypodiaceae, but the spores of the genus Pteris of the Pteridaceae (Muller 1968) also resemble this form.

Distribution

The genus Polypodiaceoisporites is known from the Tertiary and Cretaceous of both the Southern and Northern hemispheres. Polypodiaceoisporites sp. is rare at Arnot.

Genus Trilites Cookson ex Couper, 1953 Trilites sp. Fig. 6A-B Compare

Trilites ohaiensis Couper, 1953 in Couper, 1960: 41, pl. 2 (figs 7-8). Latrobosporites crassus Harris, 1965: 81, pl. 25 (figs 8-9).

Description

The spore is large and trilete with a relatively thick psilate exine. It is uniformly covered by a thin outer membrane, which closely adheres to the exine and is thrown up into low folds and wrinkles to form a dense hamulate pattern. The laesurae are long and thin and outlined by folds in the perinous membrane. The laesurae reach or almost reach the equator. It appears that the perinous membrane withdraws from a small area around the apices of the amb where the laesurae meet at the equator. This suggests that the grain is limbate. The amb of the grain is that of a broadly rounded triangle. Equatorial diameter 60 w.

26

Fig. 6.

ANNALS OF THE SOUTH AFRICAN MUSEUM

i ‘ 1 n 40 se

A-B. Trilites sp. C. Microfoveolatosporis fromensis. D. Cicatricoso- sporites sp. E-F. Reticulatasporites grandis sp. nov.

PALYNOLOGY OF THE ARNOT PIPE 27

Remarks

Despite Harris’s (1965: 81) comment that no forms resembling the new genus and species Latrobosporites crassus Harris, 1965, were then known from Austral- asia, there seems to be some measure of resemblance between TJrilites ohaiensis Couper, 1953 and L. crassus Harris, 1965. There is a resemblance between these two species and the present form, Trilites sp., although the amb of the latter is more triangular and neither of the former two species are described as perinate. Trilites ohaiensis was originally described (Couper 1953: 30) as having a verrucate—granular sculpture, but this was later revised (Couper 1960: 41) and the grains described as having a rugulate—vermiculate sculpture. Harris (1965) described the sculpture of L. crassus as consisting of low interlocking rugulae and lumina of similar size and shape.

Affinity Harris (1965) suggested that L. crassus had affinity to the extant Selaginella cathedrifolia-group as defined by Knox (1950).

Distribution Trilites sp. is rare at Arnot. Trilites ohaiensis is rare in New Zealand late

Cretaceous sediments (Couper 1960), and L. crassus is common in Palaeocene sediments from south-western Australia (Harris 1965).

Monolete spores Genus Microfoveolatosporis Krutzsch, 1959 Microfoveolatosporis fromensis (Cookson) Harris, 1965 Fig. 6C

Schizaea fromensis Cookson, 1956: 43, pl. 8 (fig. 3). Microfoveolatosporis fromensis (Cookson) Harris, 1965: 84, pl. 24 (fig. 7).

Description

The spores are monolete and oval to circular in polar view and reniform (concavo-convex) in lateral view. The laesura has distinctly raised lips for most of its length and is about one-half the total length of the spore. The exine is thick and robust and is uniformly and densely covered by regularly arranged, shallow microfoveola. Shallow furrows may connect adjacent microfoveola. The overall dimensions are very regular, approximately 80 x 60 w; length of laesura 40 yw, exine 3 w, depth of foveola 0,5 uw, 11-16 foveola per 100 pw’.

Remarks

Harris (1965) does not make it clear how Microfoveolatosporis fromensis (Cookson) Harris, 1965 differs from Microfoveolatosporis pseudodentatus Krutzsch, 1959, the type species of the genus.

28 ANNALS OF THE SOUTH AFRICAN MUSEUM

Affinity

The genus Microfoveolatosporis has affinities with the genus Schizaea of the Schizaeaceae. Spores of Schizaea pennula Swartz, an extant Columbian species, are indistinguishable from M. fromensis (Murillo & Bless 1978: 356).

Distribution

Microfoveolatosporis is known from the Tertiary of both hemispheres. The extant genus Schizaea is distributed predominantly in the Southern Hemisphere, with two species occurring in southern Africa (Welman 1970). Microfoveolato- sporis fromensis exits from the tropical African record at the Cretaceous—Tertiary boundary (Salard-Cheboldaeff 1979).

Genus Cicatricososporites Pflug & Thomson, in Thomson & Pflug, 1953

See discussion of Cicatricososporites and Schizaeoisporites in Jansonius & Hills (1976: 468-469, 2530) and Srivastava (1971: 256).

Cicatricososporites sp. Fig. 6D Compare

Cicatricososporites norissii Srivastava, 1971: 257, pl. 1 (figs 5-8).

Description

The spore is alete or possibly monolete, with canaliculate to cicatricose sculpturing. Odd ridges may bifurcate for a short distance and the sculpturing is somewhat asymmetrical, resulting in a slight spiralling appearance. No laesura was observed, but it may lie parallel to, and be almost indistinguishable from, the grooves of the sculpturing. The length of the specimen illustrated is 60 pw.

Affinity

The genus Cicatricososporites has affinities with the genus Schizaea. Srivastava (1971) stated that ‘Cicatricososporites norissii is comparable with spores of the extant species Schizaea laevigata illustrated by Selling 1946’.

Distribution

Cicatricososporites norissii is common in the lower member of the Edmonton Formation (Maastrichtian), Canada, where it is a prominent component of a flora that Srivastava (1971) suggested grew under humid conditions. The distribution of Cicatricososporites in the Palaeocene presents a strange disjunct pattern, which is reflected in the present-day distribution of the genus Schizaea (see Table 2). Only one specimen of Cicatricososporites sp. was observed at Arnot.

PALYNOLOGY OF THE ARNOT PIPE 29

Alete spores Genus Reticulatasporites Ibrahim, 1933

Ibrahim’s (1933) diagnosis of the genus Reticulatasporites was very general: ‘Spores without trilete mark, and with a measurable reticulate sculpture on the spore wall; meshes up to [or as small as ? JJ] 1 «’ (Ibrahim 1933: 38, in Jansonius & Hills 1976: 2362). It is clearly a rather insecure ‘portmanteau’ genus. Potonié & Kremp (1954), quoted in Jansonius & Hills (1976), provided a more precise diagnosis intended to accommodate a group of fungal spores.

The species described below conforms in its general features to Reticulata- sporites (sensu lato), so that in the absence of a thorough revision of the genus and its related forms it has been attributed to this genus, despite marked differences from the type species of the genus.

Reticulatasporites grandis sp. nov. Fig. 6E—-F

Etymology

The name of this species reflects the large size of the grain.

Description

The spores are atreme and spherical to subspherical—ellipsoidal. The whole surface of the spore is covered by a large-meshed, quite regularly sized reticulum, the muri formed apparently by steep folding of the outer skin. The muri themselves are never straight but ‘wriggle’ across the surface. The lumina are polygonal, mostly pentagonal, in shape. A pinnacle may be formed at the junction of the muri. The diameter of the grains is 50-60 w.

Remarks

Reticulatasporites grandis may be more similar to other species of Reticulata- sporites than it is to the type species of the genus. There is a superficial resemblance between R. grandis and Retiperiporites piacabucuensis Herngreen (1975b: 110, pl. 2 (fig. 5)), known from the Upper Senonian of Brazil.

Affinity

The affinities of Reticulatasporites grandis are open to speculation. It is unlike lycopodiaceous spores. It is more likely that it has an affinity with a bryophyte family, such as the Cleveaceae, whose members may also produce atreme spores with large reticulate features (Boros & Jarai-Komlddi 1975).

Distribution

Reticulatasporites grandis is common in the Arnot samples. There is only negative information about its wider distribution. It has apparently not been recorded in Australian late Cretaceous and Tertiary sediments. A single specimen

30 ANNALS OF THE SOUTH AFRICAN MUSEUM

encountered in late Cretaceous sediments off the south-western Cape coast and described as ‘Lycopodiumsporites facetus’ appears from the photomicrograph (McLachlan & Pieterse 1978: 875, pl. 2 (fig. 1)) to be indistinguishable from the present form.

Spores not assigned to genus Forma A Fig. 7C-D Few specimens of this spore were seen and it was unclear whether the robust verrucate structures occurred on both faces. It is probably verrucate on the distal face alone, which would place it in the genus Distaverrusporites, known from the

late Cretaceous of Nigeria and Borneo (cf. Van Hoeken-Klinkenberg 1966: 43, pl. 1 (fig. 6)). Equatorial diameter 50 w, height of verrucae 6 wp.

Forma B Fig. 8G-—H Few specimens of this spore were seen. Equatorial diameter 32-34 wp. Reticulum only on distal face. Muri 2 wu high. The junction of muri is marked by a truncated spinate process, which is an additional 3—4 w higher than the muri. This spore can probably be assigned to the genus Retitriletes, which has lycopodiaceous affinities.

Forma C Fig. 7E-F Equatorial diameter 50 w. The spore is trilete. Laesurae are straight and two- thirds the radius of the spore. Distal face is hamulate. Proximal face is covered by a perine, loosely attached to the exine and tightly folded to form a fine rugulate— hamulate pattern. Exine 3 w. This spore could perhaps be assigned to Hamulati- sporis Krutzsch, 1959 (a subgenus of Camarazonosporites), which is known from late Cretaceous and Eocene deposits in Europe (Azema & Ters 1971: 272).

Forma D Fig. 7A-B This is a very large trilete microspore with a massive perinous layer, up to 20 mw thick on the distal face and the equatorial region. This layer is coarsely and jaggedly verrucate or fossulate. The proximal face is subpsilate. The laesurae are thin and straight, or with a slight curve, and almost reach the equator. They are placed on the apex of raised triangular ridges running the length of the radial areas. This form distinctly resembles the spores of the extant dwarf tree-fern genus Lophosoria (family Lophosoriaceae) as illustrated in Murillo & Bless (1974: 252-253). This neotropical family is sometimes included in the Cyatheaceae.

PALYNOLOGY OF THE ARNOT PIPE

eg Ae or eee

404

Fig. 7. A-B. Forma D. C-D. Forma A. E-F. Forma C (Hamulatisporis).

St

32

ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 8. A. Araucariacites australis. B. Araucariacites sp. C-F. Zonalapollenites sp. B (Cingulatipollenites). G—H. Forma B.

PALYNOLOGY OF THE ARNOT PIPE 35

Pollen of Coniferae Inaperturate pollen Genus Araucariacites Cookson ex Couper, 1953 Araucariacites australis Cookson ex Couper, 1953 Fig. 8A

Granulonapites (Araucariacites) australis Cookson, 1947: 130, pl. 13 (figs 1-4). Araucariacites australis Cookson, 1947. Balme, 1957: 31, pl. 7 (figs 81-82). Kemp & Harris, 1977: 25, pl. 4 (figs 15-16).

Description

The pollen grains are large, always flattened and crumpled; inaperturate and with a thin, finely granulate exine. Diameter 50-60 pw, exine 0,5 pw.

Affinity

See discussion in Cookson (1947: 130) and Kemp & Harris (1977: 25). The affinity of A. australis is with the Araucariaceae and probably the genus Araucaria.

Distribution

Araucariacites australis is common at Arnot, reaching relative abundances of 3 per cent. This species has a world-wide distribution in the Mesozoic, but is mainly restricted to the Southern Hemisphere in the Tertiary. So far as is known it is not present in the Neogene of the African sub-continent (Thiergart er al. 1963; Coetzee 1981). It is common in lower Cretaceous sediments off the east coast of southern Africa (Scott 1976; McLachlan & Pieterse 1978), but less common in the interior (Scholtz & Deacon 1982) and south-western Cape in Cretaceous sediments. Together with other inaperturate forms, it dominates early Palaeocene or late Cretaceous assemblages from the Gamoep area (unpublished data).

Araucariacites sp. Fig. 8B Compare

Inaperturopollenites limbatus Balme, 1957: 31, pl. 7 (figs 83-84). Balmeiopsis limbatus (Balme) Archangelsky, 1977: 122-126, pl. 1. Araucariapollenites laffittei Reyre, 1973: 157, pl. 35 (figs 3-4).

Description

Outline oval or subcircular, exine 2-3 yw thick and granulate, diameter 57-74 w.

Discussion

The exine is much thicker than that of Avraucariactes australis but the granulate sculpturing is very similar. Few specimens were seen in the samples from Arnot, and although preservation of all specimens was excellent, doubt

34 ANNALS OF THE SOUTH AFRICAN MUSEUM

about its morphology remains. Possibly what is here described as a thick exine, is rather an equatorial crassitude or a particular concentric folding pattern of larger specimens of the thinner-exined A. australis. Inaperturopollenites limbatus Balme, 1957, is large, robust, granulate and inaperturate. Archangelsky (1977) has recently instituted the genus Balmeiopsis for larger spherical, granulate grains with an equatorial crassitude and an irregular aperture or thinning of the exine at one pole. Reyre (1973) erected Araucariapollenites on the rather tenuous basis of SEM-observed ultrasculptural exine features. Since few specimens were observed at Banke and an irregular aperture was not noted, a definitive description of the grain is left for later research. Palynomorph assemblages from other crater-lake deposits in the same area, but somewhat earlier in time, consistently contain A. australis and a larger and more robust morphotype.

Affinity

Araucariacites sp. is probably an extinct species of Araucaria. Balmeiopsis is found in association with twigs and cones associated with Brachyphyllum-type foliage, a leaf genus with affinity to the Araucariaceae (Archangelsky 1977). Reyre (1973) compares Araucariapollenites to the pollen of Araucaria araucana (cf. A. araucana Heusser, 1971: 12, pl. 8 (fig. 55)).

Distribution

Araucariacites sp. occurs in the Australian lower Cretaceous where it is always rare (Balme 1957: 31; Burger 1973: 100). Balmeiopsis is recorded from lower Cretaceous sediments of South America and Canada (Archangelsky 1977) and Araucariapollenites from Mesozoic sediments of north Africa (Reyre 1973).

Monosaccate pollen Genus Zonalapollenites Pflug, in Thomson & Pflug, 1953

See discussion in Dettmann (1963: 99, under Tsugaepollenites) and in Jansonius & Hill (1976: 3093, 3265).

Zonalapollenites sp. A Fig 9A—D Description

The corpus is biconvex or boat-shaped in transverse section and the grain is perisaccate in the equatorial—subequatorial region. The amb is roundly rectangu- lar to broadly elliptical. Distal and proximal faces appear to have fused so as to create a thick, laminated main body, which is granulate and rugose to indeterminately sculptured. Initial folds in the exoexine on both the proximal face (the face on to which the saccus overlaps) and the distal face mark the attachment of the saccus. The saccus is formed from a relatively thick exoexine, which is sometimes deeply folded in a radial direction and is distinctly less well developed at the opposing poles of the longest axis of the amb. It would appear that the zone of attachment of the saccus to the main body is subequatorial on the proximal and

PALYNOLOGY OF THE ARNOT PIPE 35

Fig. 9. A-D. Zonalapollenites sp. A. E. Lygistepollenites sp. F-1. Podocarpidites sp.

36 ANNALS OF THE SOUTH AFRICAN MUSEUM

perhaps also the distal face, resulting in a characteristic subequatorial dark ring when the grain is viewed from the polar position. This effect is caused by the density of the sporopollenin in the equatorial to subequatorial zone. Total diameter 33-49 w, saccus width 9-17 w, diameter of the main body 28-38 yp, thickness of main body 3—4 pw, height of the whole grain 22 wp.

Discussion

This species is similar to those described as Zonalapollenites segmentatus (Balme 1957: 33, pl. 9 (figs 93-94)) and Tsugaepollenites segmentatus (Dettmann 1963: 101, pl. 24 (figs 6f, 11-16)) but differs clearly from the description of the latter in that the present species does not have polar vesiculae. The present species also differs in the characteristic wide, dark subequatorial (taking the grain as a whole) ring. It is very difficult to photograph in transverse section. It must be pointed out that the original generic diagnosis specifies that the “saccus’ is in fact a velum formed by a fibrous baculate extension of the exine. Dettman’s (1963) diagnosis of the genus mentions only an equatorial saccus and both Zonala- pollenites sp. A and Zonalapollenites sp. B, described below, fit this more recent diagnosis.

Affinity

Dettmann (1963: 100) quotes other authors in support of a coniferous affinity — possibly to the genus Tsuga. Muller (1968) quotes Gamerro (1965) who suggests a podocarpaceous affinity for Zonalapollenites.

Distribution

The genus is present world-wide in sediments of Jurassic to Palaeogene age. It is rare in sediments of Cretaceous age off the southern African coast. Zonalapollenites sp. A is rare at Arnot.

Zonalapollenites sp. B Compare Cingulatipollenites aegyptiaca Saad & Ghazaly, 1976: 449, pl. 13 (figs 3-6).

Description

The structure is complex. The grain is biconvex to flat. The amb is subcircular to broadly elliptical. Monosaccate equatorially with the limbatus marked by a distinct, sharp, irregular line. The saccus is of medium width and it is not prominently folded in a radial or any other direction, but is rather characterized by superficial pliae. The saccus is robust and may terminate equatorially in a crassitude. The exine of the main body is relatively thin and granulate proximally and distally. The outline of the grain is irregular and the saccus may overfold the proximal surface, resulting in a rough frill-like line internal to the limbatus. On occasional grains a trilete fold may mark laesurae. The large size range makes it likely that more than one species is present. Diameter 36-70 yw, width of saccus 6-12 wp.

PALYNOLOGY OF THE ARNOT PIPE a7

Discussion

The grains are different from those of Zonalapollenites sp. A in having a relatively much smaller saccus, which is not folded in a radial direction. The saccus in the present species also does not so regularly or prominently overfold the proximal surface. The exine in the present species is granulate, while in Zonalapollenites sp. A it is granulate—rugose. Although the outline of the grain is irregular it does not show the undulate outline of Zonalapollenites dampieri, nor has the overfolding of the saccus of the proximal face been mentioned as a characteristic of Z. dampieri (Balme 1957: 32, pl. 8 (figs 88-90); Dettmann 1963: 100, pl. 24 (figs 1-5)). In other respects the present species is similar to Z. dampieri.

Saad & Ghazaly (1976) have described Cingulatipollenites aegyptiaca from the Nubia Sandstones of North Africa, which is almost certainly conspecific with certain of the forms encountered in this study. However, some of the present specimens do appear clearly saccate, rather than cingulate, so that the genus Zonalapollenites is preferred in the present context. As indicated the size range and morphological variability make it likely that more than one species is present, and perhaps cingulate as well as saccate forms. Further study of these forms is required.

Affinity Zonalapollenites sp. B is presumably coniferous, but there is no further information on its specific affinities.

Distribution

Zonalapollenites sp. B is common at Banke. The genus is known world-wide from the Jurassic to the Palaeogene. Cingulatipollenites is present in Jurassic to Upper Cretaceous assemblages from the Nubia Sandstones, North Africa (Saad & Ghazaly 1976).

Disaccate pollen Genus Lygistepollenites Stover & Evans, 1973 Lygistepollenites sp. rice IE Compare

Dacrydium cupressinum Couper, 1953, pl. 4 (fig. 35).

Description

The grain is disaccate; the corpus is circular and covered proximally and laterally with a wide layer of steep folds forming a rugulate pattern. The sacci are small and half pendent on the distal face. The sacci seem to be formed merely by larger folds of the outer skin. They are folded in a radial direction and there is no distinct zone of attachment. The distal face bears less robust sculptural elements and the sulcus, wide in the centre and narrowing towards the equatorial margins, is clear.

38 ANNALS OF THE SOUTH AFRICAN MUSEUM

Discussion

Only one specimen in a good state of preservation was observed. The grain lacks prominent proximal protuberances between the body and the proximal roots of the sacci and thus does not belong to the genus Phyllocladidites Cookson ex Couper, 1953, despite its small sacci. The grain is similar to grains of the extant species Dacrydium cupressinum (Pocknall 1981: 70, figs 2a—e), although its sacci may not be as well developed.

Affinity The affinity of the genus Lygistepollenites is with the genus Dacrydium (Section B) of the Podocarpaceae.

Distribution

Only one grain of Lygistepollenites sp. was observed at Arnot. The genus Lygistipollenites is known from the Oligocene to the present in New Zealand. It has not been recorded in late Cretaceous sediments from the interior of the African subcontinent (Scholtz & Deacon 1982) nor off the Cape (McLachlan & Pieterse 1978), but it is probably present in the Neogene (?) in the southern (Thiergart et al. 1963) and south-western Cape (J. A. Coetzee, Institute for Environmental Sciences, University of the Orange Free State, pers. comm.). It is not recorded from late Neogene sediments from Burundi (Sah 1967).

Genus Podocarpidites Cookson ex Couper, 1953 Podocarpidites sp. Fig. 9F-I Compare

Disaccites grandis Cookson, 1953: 47, pl. 2 (fig. 41).

Pityosporites grandis (Cookson) Balme, 1957: 36, pl. 10 (figs 110-111).

Alisporites grandis (Cookson) Dettman, 1963: 102, pl. 25 (figs 1-5). Haskell, 1968: 217, pl. 1 (figs 1-2).

Description

The corpus is circular in polar view and the exine is thick. The outline of the corpus is sometimes difficult to see. The sacci are large, semicircular and slightly wider than the corpus. On the distal face their roots are clearly marked, spaced wide apart and parallel, and outline a correspondingly broad tenuitas. The reticulum of the sacci is coarse and often discontinuous towards the margins of the sacci. The grain is sometimes apparently collapsed, in which case the tenuitas appears narrower and tending towards fusiform while the shape of the grain becomes oval. The preservation is usually poor. Length of the expanded grain 88-119 w, diameter of the corpus 60-63 pw, length of the sacci 68—75 ww, breadth of the sacci 25-32 yw, distance between the zones of attachment on the distal face 25-33 p, exine of irregular height, 4-8 wp.

PALYNOLOGY OF THE ARNOT PIPE 39

Discussion

Haskell (1968: 217) provides a satisfactory description on the range of variation in Alisporites grandis. The dimension of the grains that he measured are very similar to those of Podocarpidites sp. He described two states for the form—a diploxylonoid and a haploxylonoid state—which may correspond to the ‘expanded’ and ‘collapsed’ states described here. Despite regarding the present form as conspecific with A. grandis (Cookson) Dettmann, 1963, as described by Haskell (1968), and since the ‘expanded’ or diploxylonoid state (which shows non-Alisporites-like characteristics) is most common at Banke, it was not considered justified to place it in the genus Alisporites. It is beyond the scope of the present paper to propose new combinations, and it is therefore merely noted that the genus Alisporites Daugherty, 1941, has been redefined (Jansonius 1971; Jansonius & Hill 1976: 68-69) and, in the opinion of the present author, the diploxylonoid state of Podocarpidites sp. and of A. grandis as redescribed by Haskell (1968) does not permit the inclusion of these species in the revised diagnosis of the genus Alisporites. Jansonius (1971) also suggested a pterido- spermous affinity for Alisporites, while the morphology of the present form suggests a podocarpaceous affinity. The present form is probably comparable to that described as Podocarpidites sp. by Sah (1967: 44, text-fig. 13, pl. 4 (fig. 11)) from the Neogene of Burundi.

Affinity

The affinity of Podocarpidites sp. is probably with the Podocarpaceae, section Eupodocarpus (which includes the African species Podocarpus latifolius, P. elongatus and P. henkelii) or section Stachycarpus (A. R. H. Martin 1959; Pocknall 1981). On overall size alone the New Zealand members of what has been regarded as the most primitive section of the family, Stachycarpus (Bucholtz & Gray, 1948), compare most closely with the present form. The rarity and state of preservation of the specimens precludes finer morphological comparisons.

Distribution

Alisporites grandis is known from the upper Jurassic and lower Cretaceous strata in Australia and Canada (Haskell 1968) and from Cretaceous strata off South America (Archangelsky & Gamerro 1967). It is common in the Australian lower Cretaceous. It is not recorded in Cretaceous sediments of DSDP 361 off the south-western Cape coast (McLachlan & Pieterse 1978), nor is it present in the Knysna lignites (Thiergart et al. 1963). It is present in the Neogene of central Africa (Sah 1967), where it is very rare. Podocarpidites sp. is rare at Arnot.

Podocarpidites kamiesbergensis sp. nov. Fig. 1OA—D

Etymology This species is named after the nearby Kamiesberg Mountains.

40 ANNALS OF THE SOUTH AFRICAN MUSEUM

eal :

ce ” |

Fig. 10. A-D. Podocarpidites kamiesbergensis sp. nov. E-J. Podocarpidites riembreekensis sp. nov. K-L. Arecipites sp. B. M-—P. Arecipites sp. A.

PALYNOLOGY OF THE ARNOT PIPE 4]

Description

Small, disaccate pollen grains, the corpus trapeziform in shape, but somewhat arched proximally. The semi-hemispheric sacci are attached laterally at a low angle. The grain is often not fully expanded, in which case the sacci appear more pendent. The exine is relatively thick proximally and laterally, and vermiculate to foveolate. The distal tenuitas is relatively broad and parallel-sided and the infrareticulation of the sacci is robust, clear and mostly perfect. In polar view the sacci are as broad as the corpus. Corpus circular in polar view. Outline of the sacci regular. Total length of expanded grain 36—41 uw; height of corpus in lateral view 20 w, width of corpus 23-26 uw, length the same; breadth of sacci 10 pw, depth 16 pw, length of sacci 20-23 yw, distance between lines of attachment of sacci on the distal face 8-10 yp.

Discussion

Podocarpidites kamiesbergensis is smaller in size than the smaller species of Podocarpidites described in the available literature, such as P. congoensis Sah (1967: 43, pl. 4 (figs 5-6, 9-19)). Podocarpidites kamiesbergensis may be the same as P. knysnanus Thiergart, Frantz & Raukopf, 1963, described from the Knysna lignites, but this form is inadequately characterized and illustrated (Thiergart er al. 1963).

Affinity

The affinities of P. kamiesbergensis are with the Podocarpaceae, especially the section Afrocarpus (including Podocarpus gracilior and P. falcatus) as defined by A. R. H. Martin (1959). It would be difficult to distinguish between the pollen of P. falcatus and Podocarpidites kamiesbergensis.

Distribution

Podocarpidites kamiesbergensis is common at Arnot, reaching a relative abundance of 5 per cent. It is not present in the late Cretaceous sediments from the interior (Scholtz & Deacon 1982) or off the south-western Cape (McLachlan & Pieterse 1978), but is possibly present in the Neogene (?) Knysna lignites. However, the description of P. knysnanus Thiergart, Frantz & Raukopf, 1963, does not permit identification with the present species.

Podocarpidites riembreekensis sp. nov. Fig. 10E—J Etymology

This species is named after the nearby farm Riembreek, which is also the site of several crater-lake deposits.

Description

Medium-sized disaccate pollen grains. The corpus has a rounded rhomboidal shape in polar view and is trapeziform in side view. The sacci are laterally attached at a low angle and are rigid, hemispherical and slightly wider than the

42 ANNALS OF THE SOUTH AFRICAN MUSEUM

corpus in polar view. The infrareticulum of the sacci is greatly reduced so that only isolated sections of muri remain. The proximal and lateral surfaces of the corpus are covered by sharply defined, densely packed rugulate to verrucate or vermiculate structures, and the exine thickens in the proximal area to form a distinct cappa. Proximally each saccus is attached to the corpus by two crassitudes, which are not always prominently protuberant. Such protuberances are not so well developed around the remaining lateral and distal zones of attachment, but are developed enough to form a thick rugose collar that constitutes the roots of the sacci. The roots are marked, but least robust on the distal face where the sacci are separated by a wide, parallel-sided tenuitas.

Total length of grain 40-64 w; width of corpus 23-33 mw, length of corpus 25-35 mw; length of sacci 25-39 w, depth of sacci approximately 14 w, breadth of sacci approximately 25 w, exine of sacci approximately 1 wp.

_ Discussion

The grain has very distinctive morphology. The infrareticulum of the sacci is so reduced that it may be entirely absent over large areas. The exine of the sacci is relatively thick. In polar view the four proximal crassitudes are marked and produce the characteristic rhomboidal shape of the corpus. The proximal and lateral sculpturing is distinct and robust, and is truncated as the distal surface is approached. The proximal protuberances are part of the robust collar that attaches the sacci to the corpus, and differ from the more localized structures described for Phyllocladidites. The much larger sacci also distinguish this species from Phyllocladidites.

Affinity The affinity of Podocarpidites riembreekensis is with the Podocarpaceae, but perhaps not with any extant genus.

Distribution

Podocarpidites riembreekensis is common at Arnot. As far as is known this form has not been recorded elsewhere.

Pollen of Angiospermae Monoaperturate pollen Monocolpate pollen Genus Arecipites Wodehouse, 1933

‘The genus Arecipites Wodehouse, 1933 was emended [sic] by Anderson (1960) to include only those reticulate monosulcate pollen grains which have, among other characters, lumina less than 0,5 wu in diameter. Reticulate monosulcate forms whose lumina width exceeds 0,5 w were referred by Anderson

to the genus Liliacidites Couper, 1953’—Chmura (1973: 104). This procedure has been generally accepted and is the one followed here.

PALYNOLOGY OF THE ARNOT PIPE 43

Arecipites plectilimuratus Chmura, 1973 Fig. 11A—B Arecipites plectilimuratus Chmura, 1973: 104, pl. 21 (figs 1-3).

Description

Monosulcate; elongate—ellipsoidal in polar view. The sulcus extends the whole length of the grain and may even transgress the ends of the grain. The margins of the sulcus are faint and irregular since the exine thins as the sulcus is approached. The sulcus is open and, despite the irregularity, more or less parallel-sided for its whole length. The exine is relatively thick and the reticulum is distinct and uniform over the whole of the grain, except when the sulcus is approached and the reticulum becomes indistinct. Muri are approximately the same width as the lumina and mostly duplibaculate. Length of illustrated grain 40 pw, width 28 pw, exine 2 yp.

Discussion

For comparison with other species of Arecipites see Chmura (1973: 104). The genus is a generalized morphological type and no specific identity of the plants involved need be supposed.

Affinity

The affinity of Avicipites plectilimuratus is with a broad monocotyledonous group including the Amaryllidaceae, Iridaceae and Liliaceae. The pollen of southern African Monocotyledonae is not sufficiently well known to enable one to suggest closer affinities with any taxa of the local flora.

Distribution

Arecipites plectilimuratus is rare at Arnot. It is also rare in the late Cretaceous of California.

Arecipites sp. A Fig. 1OM-—P

Compare

a

Arecipites reticulatus (van der Hammen) Anderson, 1960: 18.

Description

Small, monosulcate pollen, elongate—oval with rounded ends. The sulcus is long, has no margo and reaches the ends of the grain. The exine is relatively thick and clearly differentiated into a nexine and a tectate sexine. The surface of the grain is uniformly covered by microscrobiculi. Length of the grain 23-25 yw, exine 1—2 p thick, scrobiculi 0,2 pw.

44

Fig. 11.

ANNALS OF THE SOUTH AFRICAN MUSEUM

A-B. Arecipites plectilimuratus. C-D. Liliacidites sp. B. E-F. Clavatipollen- ites spp. (SEM). G-L. Clavatipollenites sp. A. M-N. Clavatipollenites sp. B. O-Q. Clavatipollenites sp. C. R-T. Monocolpopollenites sp. B.

PALYNOLOGY OF THE ARNOT PIPE 45

Discussion

Arecipites sp. A is a small, robust, distinctive grain that is dissimilar to A. plectilimuratus. It differs from A. reticulatus in its finer scrobiculi and thicker exine.

Affinity Arecipites sp. A has monocotyledonous affinities.

Distribution

Arecipites sp. A is rare at Arnot.

Arecipites sp. B Fig. 1OK-L

Description

The grain is ellipsoidal with a thin and indistinct colpus, which runs the length of the grain. The exine is relatively thick and the sexine and nexine layers are clearly differentiated. The sexine is psilate to indeterminately sculptured and appears finely columellate. Dimensions of illustrated specimen 38 X 26 w, exine 1-2 p.

Affinity No information exists regarding the affinity of Arecipites sp. B.

Distribution

Arecipites sp. B is rare at Arnot.

Genus Liliacidites Couper, 1953 Liliacidites sp. A Fig. 12E—H

Description

The grains are ellipsoidal to elongate—ellipsoidal in polar view. The sulcus in expanded grains is wide with parallel sides, and stretches the length of the grain. The meshes of the complex reticulum become smaller as the sulcus is approached until a margo is formed by a narrow zone of unbroken exine. The exine may also become thinner towards the colpus, but this was not definitely established. Elsewhere the reticulum forms a complex, irregular, non-perfect pattern and is simplicolumellate. The exine is relatively thick and two layers are clearly distinguishable. Sexine and nexine are of similar height. Length of grain 29-36 p, width of expanded grain in polar view 30 uw, sulcus width 3,5-5 w, exine approximately 2 w, lumina 1-3 wp.

46 ANNALS OF THE SOUTH AFRICAN MUSEUM

Discussion

Liliacidites sp. A appears to be similar to those described as Liliacidites intermedius Couper, 1953, but is distinguished from that species by the characteristic reduction of the reticulum in the vicinity of the colpus, and in that the reticulum of the present species is not reduced towards the ends of the grain.

Affinity

The affinity of Liliacidites sp. A is perhaps with the genus Chamaedorea of the Palmae. Similar forms are also found in the Butomaceae and Liliaceae. The extant genus Chamaedorea contains rather unusual small, reed-like palms found in tropical deciduous thickets (Lozano-Garcia 1979).

Distribution

Liliacidites sp. A is common at Arnot.

Liliacidites sp. B Fig. 11C-—D

Description

Monocolpate, irregular elongate—ellipsoidal. Narrow sulcus with distinct margo stretches the full length of the grain. The tectum is imperfect. Crassisexinous. The reticulum is irregular, imperfect and robust, so that the sculpturing appears reticulate-rugulate. The columellae may be horizontally elongated so that the sculpturing gives the appearance of broken stretches of muri. Length of grain illustrated 36 w, width 22 pw, exine 3 w.

Discussion

Liliacidites sp. B is most unusual in the reduction in height of the columella and a corresponding increase in the depth of the tectum.

Affinity The affinity of Liliacidites sp. B is perhaps with the Liliaceae (cf. Lilium longiflorum (Huang 1972: 266, pl. 173)).

Distribution

Liliacidites sp. B is very rare at Arnot.

Genus Clavatipollenites Couper, 1958

See discussions in Dettmann (1973: 11) and Kemp & Harris (1977: 55). The genus is well represented at Banke with at least three forms being present, one of which is common.

PALYNOLOGY OF THE ARNOT PIPE 47

Clavatipollenites sp. A Fig. 11G—L Compare Clavatipollenites sp. Dettmann, 1973: 11, pl. 2 (figs 8-11).

Description

The grains are monocolpate and subspheroidal to slightly ellipsoidal— spherical. The colpus is usually ulcerate with a broken and irregular margin in the sexine. It is irregular in outline and usually more or less isodiametric. Occasional grains have a clean, straight margin in the sexine (Fig. 111) and others appear trichotomosulcate (Fig. 11J). Sexine and nexine are about the same height. The reticulum is perfect and the muri simplicolumellate. The swollen heads of the columellae and thus ‘lumpiness’ of the muri can be seen in the SEM photomicrographs (Fig. 11E—F). Further SEM work may confirm whether the ‘lumpiness’ (Kemp & Harris 1977) or ‘beaded’ characteristics (Coetzee 1981) of the exine can be of taxonomic significance. It would appear from the limited SEM work done in the present study that in Clavatipollenites sp. A the ‘beadedness’ is caused by suprategillar microconi mounted on the branches of the reticulum, while in Clavatipollenites sp. C (described below) the ‘lumpiness’ of the muri may be caused by the swollen heads of the columellae alone. Length of grain usually between 22-27 uw, but occasional grains up to 31 mu, exine 1,5-3 w, lumina approximately 1 mw, sulcus usually in the order of 5—8 w diameter, but may be longer.

Affinity

See discussions in Dettmann (1973: 11), Kemp & Harris (1977: 56) and Muller (1981: 9). Affinity of the genus Clavatipollenites is probably with the Chloranthaceae (Doyle 1969).

Distribution

The distribution in time and space and a suggested pattern of extinction of the Clavatipollenites—Ascarina complex is discussed in Muller (1981: 9-12). Their suggested pattern of extinction needs to be revised since Clavatipollenites has been recorded at Arnot and in the Neogene in the south-western Cape (Coetzee 1981). Observations from the Botswana region (Scholtz & Deacon 1982), however, confirm that in late Cretaceous assemblages dominated by Ephedripites (and Cretacaeisporites), Clavatipollenites is not present. Clavatipollenites sp. A is common at Arnot.

Clavatipollenites sp. B Fig. 1LM-N Description

Monocolpate, subspherical to ellipsoidal—spherical. Sulcus relatively smaller than in Clavatipollenites sp. A and more circumscribed. Exine thick and

48 ANNALS OF THE SOUTH AFRICAN MUSEUM

crassinexinous. Recticulum relatively fine. Length 24 uw, width 19 w, nexine approximately 2 w, sexine 1 w, lumina 1 wp.

Discussion Clavatipollenites sp. B is distinguished from Clavatipollenites sp. A by the prominent dense nexine, relatively thin sexine, and fine reticulation.

Distribution Clavatipollenites sp. B is rare at Arnot.

Clavatipollenites sp. C Fig. 110-Q

~ Description

Monocolpate, ellipsoidal—spherical with a long closed colpus, which, as usual for Clavatipollenites, has ragged broken edges in the sexine. The exine is relatively thick with sexine and nexine about the same height. Markedly robust columellae support a perfect reticulum. Columellae are only placed beneath wide areas of the tectum formed at the junction of individual branches of the tectum. Length of grain 32 uw, width 26 w, exine 3-4 yw, lumina 1-2 p.

Discussion

Clavatipollenites sp. C is clearly distinguishable from the former two species by its greater size, long sulcus, and robust columellae and tectum.

Distribution

Clavatipollenites sp. C is rare at Arnot.

Genus Monocolpopollenites Pflug & Thomson, in Thomson & Pflug, 1953

See discussion in Nichols et al. (1973) and Jansonius & Hill (1976: 1691).

Monocolpopollenites sp. A Fig. 12A—D Compare Monocolpopollenites sp. Jardiné & Magloire, 1963: 211-212, pl. 8 (figs 31-32).

Description

Monocolpate, subcircular to ellipsoidal in polar view and ellipsoidal in equatorial view. The colpus has a complex structure; it is parallel-sided and reaches the ends of the grain. The lips of the colpus are folded inwards and

PALYNOLOGY OF THE ARNOT PIPE 49

Fig. 12. A-D. Monocolpopollenites sp. A. E-H. Liliacidites sp. A. I-J. Forma E (monocolpate pollen). K-—M. Milfordia hypolaenoides. N. Milfordia sp.

50 ANNALS OF THE SOUTH AFRICAN MUSEUM

thickened, and on the inner margins of the lips a scabrate row of sculpturing is formed, consisting perhaps of closely packed, small verrucae. This is a very characteristic feature. The exine is thick, tectate and psilate, and a finely punctate perinous membrane envelops the grain. This layer sometimes closely adheres to the surface of the grain and at other times separates from the exine. Few specimens were observed, but from the size range it is possible that two species may be present. Length 26-39 w, width 18-34 uw, exine 2,5—3 w, width of colpus measured from the outer margins of the interior sculptured lips 5-8 w.

Affinity The affinity of Monocolpopollenites sp. A is not known.

Distribution

Monocolpopollenites sp. A is rare at Arnot. Monocolpopollenites sp. Jardiné & Magloire, 1963, is known from Turonian to Maastrichtian time ranges from Senegal and the Ivory Coast.

Monocolpopollenites sp. B Fig. 11R-T

Description

Grains monocolpate, rarely trichotomosulcate; ellipsoidal to subcircular. The colpus stretches the length of the grain, is parallel-sided and relatively wide. The lips are raised and decorated with short folds or verrucae. The ends of the colpus are abruptly truncated and edged with verrucae or bits of exine. The exine is relatively thin and is sparsely and irregularly decorated with isolated spinosa. Length of grain 30-34 uw, width 20-23 uw, width of colpus approximately 4 uw, exine approximately 1 wp.

Discussion

Monocolpopollenites sp. B is distinct from Monocolpopollenites sp. A in having a much thinner exine and lacking a perinous layer. The latter may be a weak criterion considering that only a few grains were observed. The sparse, but always present, isolated spinosa of Monocolpopollenites sp. B are also distinctive.

Affinity

The affinity of Monocolpopollenites sp. B is perhaps with the Palmae, although as far as could be ascertained no extant Palmae display similar sculpturing or end-aperture morphology (Sowumni 1972; Kedves 1980).

Distribution

Monocolpopollenites sp. B is rare at Arnot.

PALYNOLOGY OF THE ARNOT PIPE Sl

Monoporate pollen Genus Milfordia Erdtman, 1960 Milfordia hypolaenoides Erdtman, 1960 Fig. 12K—M Milfordia hypolaenoides Erdtman, 1960: 46, pl. 1 (fig. a). Martin, 1973: 37, figs 163-165.

Description

The pollen is monoaperturate and spherical to subspherical. The pore is relatively large, circular or elliptical, and ulcerate, with the margins ragged and often with loose pieces of exine in the mouth. The pollen has a slightly irregular, undulating outline and the exine is relatively thick, scrobiculate and possibly finely fossulate. Diameter of grain 25-32 « on SEM photomicrographs, 31-43 yu on the light microscope; aperture diameter 11-20 w, occasionally smaller and clotted with bits of exine; exine 1-2 wp.

Discussion

Although Elsik (1968: 313) and Partridge (in Stover & Partridge 1973: 262) proposed generic diagnoses for types of restionaceous pollens that would include both the smaller, porate or graminoid-type aperture and the larger centro- lepidoid-type aperture (Chanda 1966), there is little value in using such a broad concept on a specific level, as Partridge has done in Milfordia homeopunctata Partridge, in Stover & Partridge, 1973. Since Chanda’s work (1966) it has been clear that a distinction between the two types is significant in terms of the phylogeny and plant geography (see Johnson & Briggs 1981: 458).

The normal aperture in the Arnot specimens of Milfordia hypolaenoides is relatively large and ulcerate and clearly of the centrolepidoid type (Chanda 1966). The aperture is similar to the ‘Hypolaena’-type illustrated in Couper (1960: 62, pl. 9 (figs 26—27)) and H. A. Martin (1978: 191, pl. 7 (fig. X)) although, unfortunately, as Muller (1981: 105) points out, only one species of the genus Hypolaena has such a pore.

Erdtman (1938) and Chanda (1966) have suggested, on the basis of the pollen morphology of extant species, an evolutionary sequence beginning with the ‘primitive’ Centrolepidaceae, through those Restionaceae with centrolepidoid apertures and the Restionaceae with graminoid apertures, to the ‘advanced’ Flagellariaceae and Poaceae (Chanda 1966: 396). Following the work of Hochuli (1979), Muller (1981: 105) has noted the importance of the ‘relatively small rounded—porate aperture with a more or less irregular margin and an indistinct annulus which is transitional between the centrolepidoid and graminoid aperture type’ in the early fossil record of the Restionaceae. This type of aperture has been named the Restio subverticillatus-type by Muller (1981) and corresponds to the ‘Restio’-type of H. A. Martin (1978: 191, pl. 7 (fig. W)). The latter is once again a

Sy ANNALS OF THE SOUTH AFRICAN MUSEUM

rather unfortunate choice of name by Martin as the R. subverticillatus-type does not include many members of the genus Restio (Chanda 1966).

It is clear that the evolutionary sequence proposed by Erdtman (1938) and Chanda (1966) is not supported by the fossil record. All three apertural states of the Restionaceae (graminoid, centrolepidoid, and transitional) are at present known from late Cretaceous or Palaeocene sediments (Hochuli 1979; Salard- Cheboldaeff 1979; Muller 1981; present study). It seems, however, that none of the early forms show the extreme development of either centrolepidoid or graminoid apertures that can be found in some extant species. In particular the sharply protruding graminoid apertural state is as yet known only from possibly early Neogene sediments (Thiergart et al. 1963).

The present evidence, confirming the early existence of the centrolepidoid apertural state, indicates that the phylogenetic relationships inferred by Johnson . & Briggs (1981) for the Restionaceae may need revision.

Affinity

Chanda (1966) and Ladd (1977) discuss the morphology of the pollen of the Centrolepidaceae, Restionaceae and Flagellariaceae. Most modern Australian species of Restionaceae have the centrolepidoid (Chanda 1966) or ‘Hypolaena’- type apertures (Couper 1960; H. A. Martin 1978), while almost all southern African species have the graminoid type (Chanda 1966). The present form, Milfordia hypolaenoides, is therefore morphologically similar to extant Australian Restionaceae rather than to the majority of southern African species. However, the pollen of one southern African genus, Thamnochortus (Chanda 1966; H. P. Linder, Bolus Herbarium, University of Cape Town, pers. comm.), is comparable to the present form. Thamnochortus is unusual in a number of other respects amongst the southern African Restionaceae, and the indications from taxonomic studies are that it has had a long, isolated evolutionary history in the subcontinent (H. P. Linder, pers. comm.). Milfordia hypolaenoides is also similar to the pollen of Centrolepsis and Gaimardia of the Centrolepidaceae, but because of the modern distribution of this family, an affinity between it and M. hypolaenoides is considered unlikely.

Distribution

Milfordia hypolaenoides Martin, 1973, has been recorded from the late Cretaceous of North America (Jarzen 1978) and in the Lower Palaeocene of Europe where it continues into Miocene time ranges (Muller 1981). In Australia it may be present from the lower Eocene (Stover & Partridge 1973) and is common in younger sediments. Restionaceous forms were not recorded in late Cretaceous sediments off the south-western Cape coast (McLachlan & Pieterse 1978). However, typically southern African Restio-type graminoid forms only were recorded, and in great abundance, from the Neogene (?) Knysna lignites (Thiergart et al. 1963). Milfordia hypolaenoides is common at Arnot.

PALYNOLOGY OF THE ARNOT PIPE 53

Milfordia sp. Fig. 12N Compare

Restioniidites homeopunctatus Hekel, 1972: 15, pl. 6 (fig. 30). Restioniidites pascuali Archangelsky, 1973: 385, pl. 9 (figs 4-8).

Description

The grain is large, ellipsoidal and monoporate. The pore is relatively small and circular and the margin neatly defined. The exine is of medium thickness, finely scrobiculate, and the outline of the grain is smooth. The dimensions of the single illustrated grain are 53 x 39 wy, the pore is 8 uw wide, the exine 2 uw thick.

Discussion

Milfordia sp. is distinguished from M. hypolaenoides by its aperture morphology, smoother exine and ellipsoidal shape. The present form is similar to the ‘Restio subverticillatus’-type discussed in Muller (1981: 105). Since only one specimen was observed it was not assigned to either Restioniidites homeopuncta- tus or R. pascuali, with which it is compared.

Affinity

The affinity of Milfordia sp. is thought to be with some southern African Restionaceae, especially ‘Restio subverticillatus’ (see discussion on M. hypo- laenoides).

Distribution

Pollen of the ‘Restio subverticillatus’-type is known from the Maastrichtian of north Africa (Jardiné & Magloire 1963) and the Palaeocene of south and north America and Europe (Muller 1981). In Australia it is known from lower Eocene to Miocene sediments (Hekel 1972; Stover & Partridge 1973). Only one specimen was observed at Banke.

Dicolpate pollen Genus Dicolpopollis Pflanzl, 1956 Dicolpopollis sp. Fig. 13A—D

Description

The grain is dicolpate (disulcate?) and ellipsoidal. The colpi are three- quarters the length of the grain and have distinct margo. The colpi are usually on opposite sides of the grain (Fig 13C—D) but are occasionally on the same face (Fig. 13A—B). Crassisexinous. The reticulum is fine and regular and the lumina are circular. Length 37-43 w, width 22-30 w, lumina approximately 0,5 yp.

54 ANNALS OF THE SOUTH AFRICAN MUSEUM

oN:

Fig. 13. A-D. Dicolpopollis sp. E-I. Triorites operculatus sp. nov. J—M. Triorites sphericus sp. nov. N. Triorites harrissii. O-P. Proteacidites sp. A. Q-R. Proteacidites sp. B.

PALYNOLOGY OF THE ARNOT PIPE 35)

Affinity

Disulcate pollen is found in extant members of the Amaryllidoideae of the Amaryllidaceae, in some genera of the Iridaceae, in the Tofieldieae of the Liliaceae, and in the Palmae (Chmura 1973). However, the disulcate pollen of Monimiaceae most closely resembles Dicolpopollis sp.

Distribution

Dicolpopollis sp. is more common towards the base of the Arnot sequence.

Monocolpate pollen not assigned to genus Forma E Fig. 12I-J

Description

The grain is monocolpate with a relatively thin exine and all the specimens seen had an irregular amb but were not folded. The colpus has no margo and in all specimens was on the edge of the grain. Reticulate; the reticulum is quite coarse and duplicolumellate. The muri and lumina are of about the same width and the columellae usually encircle a lumina. Dimensions of illustrated specimen 5 < 26 IL:

Affinity Forma E grains resemble the pollen of the extant palm species Areca warburgiana (Sowumni 1972, pl. 1).

Distribution

Forma E grains are rare at Arnot.

Triaperturate pollen Triporate pollen Genus Triorites Cookson ex Couper, 1953 See discussion in Muller (1968: 14).

Triorites operculatus sp. nov. Fig. 13E-I Compare Triorites festatus Muller, 1968: 15, pl. 3 (fig. 10).

Etymology

The specific name refers to the presence of an operculum.

56 ANNALS OF THE SOUTH AFRICAN MUSEUM

Description

Triporate, spherical grains with an exine of medium width, which appears subpsilate to granulate under the light microscope. Under the SEM it can be seen that the exine is, in fact, psilate with minute, relatively closely spaced tuberculata or spinules, giving the granular appearance. The pores are circular and are surrounded by a low annulus of intermediate width, which is formed by the sexine being slightly raised away from the nexine, i.e. forming a simple low vestibulum. The vestibulum is so small and often inconspicuous that the grain can hardly be described as vestibulate. The sexine may also thicken slightly in the region of the pore. The pore has an operculum bearing the same minute tuberculata and attached to a psilate underlying layer. The operculum is sometimes absent. The exine is relatively thin and the grain is usually folded, this folding following no particular pattern. Two layers are distinguishable in the exine. Diameter . 27-30 mw, exine approximately 1 w, diameter of pore approximately 2 uw, width of annulus 1 p.

Discussion

Triorites operculatus is different from T. festatus Muller, 1968, in having an operculum. The pores and annulus of 7. operculatus are also smaller.

Affinity

Muller (1968: 15-16) has warned that in the case of forms that show a generalized, primitive type of pore (as in 7. operculatus), affinity with an extant family will be almost impossible to determine with any certainty. Broad affinity is possibly with certain families of the Hamamelidales (Takhatajan 1969), including the Ulmaceae, Carpinaceae, Corylaceae, Casuarinaceae and Myricaceae. Oper- culate forms are not uncommon in these families; all the Carpinaceae (some of which are triporate), some species of the genus Celtis of the Ulmaceae (e.g. Celtis iguanea—Erdtman 1952), and some of the Myricaceae are operculate.

Distribution

Triorites operculatus is the dominant form at Arnot, constituting 54 per cent in one sample, and sometimes occurring in clusters. Triorites festatus is present from the late Cretaceous in Borneo, but is more frequent in the late Palaeocene— Eocene and follows the same pattern in tropical west Africa (Salard-Cheboldaeff 1981). The genus Celtis is known from leaf impressions of Maastrichtian age from the Cameroons (Salard-Cheboldaeff 1981).

Triorites sphericus sp. nov. Fig. 13J-M Etymology

The specific name refers to the robust spherical shape of the grain and the fact that the grain is seldom deformed.

PALYNOLOGY OF THE ARNOT PIPE Sy

Description

Triporate grain, spherical and robust. The exine is relatively thick and crassisexinous. The pores are circular to equatorially elongated and are surrounded by a clear annulus. The point at which the annulus begins is marked by a sharp line of the exine surface. The annulus is formed by the sexine separating and rising abruptly away from the nexine. The exine is subpsilate to faintly rugose and undulate. In some grains it appears that the exine may thicken slightly towards the mesocolpia in the equatorial region. Equatorial diameter 20-24 w, diameter of pore opening approximately 2 w, diameter of pore and surrounding annulus 6—7 pw, exine 2-4 w.

Discussion

Triorites sphericus differs from T. operculatus in its smaller size, relatively thicker crassisexinous exine, lack of operculum and in sculpturing details of the exine. Unlike T. operculatus the grain of T. sphericus is seldom folded in any way.

Affinity See note on affinity of Triorites operculatus. Triorites sphericus 1s perhaps

morphologically closer to species of the Betulaceae or Corylaceae than to those of the Ulmaceae, Carpinaceae or Casuarinaceae.

Distribution

Triorites sphericus is common at Arnot.

Triorites harrissit Couper, 1960 Fig. 13N Driorites harrissii Couper, 1960: 67, pl. 12 (fig. 2). Hekel, 1972: 17, pl. 5 (fig. 7).

Description

Triporate, angulaperturate with triangular amb. Exine is relatively thick with nexine and sexine distinct. Subpsilate, pores narrow. Equatorial diameter of illustrated specimen 31 yw, exine 2 w, pore diameter 2 w.

Discussion

Triorites harrissii differs in shape from the two previous species. The Arnot specimens are very similar to the illustrated specimens of Triorites harrissii of Couper (1960) and Hekel (1972).

Affinity The affinity of TJ. harrissii is with the Casuarinaceae or Myricaceae—more likely the former.

58 ANNALS OF THE SOUTH AFRICAN MUSEUM

Distribution

Triorites harrissii has a range from the Palaeocene to the present in the Australia-New Zealand area. Only three specimens were observed at Arnot.

Genus Triporopollenites Pflug & Thomson, in Thomson & Pflug, 1953

There is some confusion as to what generic designation should be used for forms with the general morphology of the species described below. The problem arises in that four genera have been used to describe broadly similar morpho- types. These are Proteacidites Cookson ex Couper, 1953, Triporopollenites Pflug & Thomson, in Thomson & Pflug, 1953, Echitriporites van Hoeken-Klinkenberg, 1966, and Propylipollis Martin & Harris, 1974. A. R. H. Martin & Harris (1974) have also discussed the problems raised by the burgeoning of the genus _ Proteacidites and proposed two additional genera—the three being distinguished mainly in apertural morphology.

Examples of forms that are broadly related morphologically and have been classified under the above four genera, are the following: Proteacidites tuberculi- formis Harris, 1965 (p. 92, pl. 29 (figs 5—7)); P. longispinosus Jardiné & Magloire, 1963 (p. 218, pl. 7 (figs 15-17)); Echitriporites trianguliformis van Hoeken- Klinkenberg, 1966 (p. 21, pl. 42 (fig. 7)); and Triporopollenites ambiguus Stover, in Stover & Partridge, 1973 (p. 269, pl. 21 (fig. 7)). Proteacidites tuberculiformis Harris, 1965, was later transferred by A. R. H. Martin & Harris (1974) to Propylipollis although, according to Harris’s original description, it lacks the diagnostic post-atrium. Martin & Harris also excluded Proteacidites longispinosus from Proteacidites Cookson ex Couper, 1953 (sensu Martin & Harris), without proposing an alternative genus. To add to the confusion Boltenhagen (1978) instituted a new species Proteacidites sigalli Boltenhagen, 1978, which he compared to Echitriporites trianguliformis, and suggested, on very poor grounds, that P. sigalli could be compared with pollen of the extant proteaceous genus Spatalla.

No new genus is proposed here but it is suggested that a genus might be considered that would include medium to large triporate forms with simple pore structures, whose sculpturing is of scattered apicula, spinosa or micro-echina, but which are not echinate, i.e. forms comparable, for example, to the pollen grains of the extant proteaceous genera Telopea and Embothrium (Erdtman 1952: 356).

Triporopollenites namaquensis sp. nov. Fig. 14A-E Compare

Triporopollenites ambiguus Stover, in Stover & Partridge, 1973: 269, pl. 21

(fig. 7). Proteacidites tuberculiformis Harris, 1965: 92, pl. 29 (figs 5-7).

PALYNOLOGY OF THE ARNOT PIPE

S04

Fig. 14. A-E. Triporopollenites namaquensis sp. nov. F-J. Propylipollis meyeri sp. nov.

a9

60 ANNALS OF THE SOUTH AFRICAN MUSEUM

Etymology

The species is named after the region Namaqualand, which in turn takes its name from its indigenous inhabitants, the Nama.

Description

Triporate, angulaperturate pollen with a triangular amb and straight to slightly convex sides. The grains are large and, relative to their size, thin-walled, so that they are mostly irregular, flattened and folded. Sexine and nexine can be distinguished and the exine is crassinexinous. The thin exine is finely punctate and bears solitary spinules mounted on broader bases, sparsely but more or less regularly distributed on its surface. The pollen is very variable in size and this suggests the possible presence of more than one species. The exine thickens slightly at the pore margins to form a distinct annular ring, which is, however, difficult to observe in polar view. The pore is circular to equatorially elongated. Equatorial diameter 45-90 w, pore diameter 6-10 uw, width of annulus approxi- mately 2 uw, height of spinosa 2 pw.

Discussion

A few species of broadly similar morphology are known (see discussion on genus). Triporopollenites namaquensis differs from Proteacidites tuberculiformis in being spinulate (not verrucate), in the sparseness of its ornamentation, and in having a distinct annulus—although, as stated, it is easy to miss this feature. Except for size, the present species being considerably larger, 7. namaquensis is very similar to T. ambiguus.

Affinity Triporopollenites namaquensis perhaps has affinities with members of the subfamily Grevilleoideae of the Proteaceae.

Distribution

The species is common at Arnot. Germeraad et al. (1968: 312) in discussing the distribution of the similar morphotype, Echitriporites, stated: “The more triangular grains with fewer and smaller spines are more common in the Upper Cretaceous of northern South America, whereas the more rounded grains with slightly more and larger spines are more common in the Eocene.’ The similar Australian form 7. ambiguus is known from Palaeocene and Eocene sediments.

Genus Proteacidites Cookson ex Couper, 1953

The generic name is used here in the restricted sense as defined by A. R. H. Martin & Harris (1974). See also discussion for Triporopollenites (p. 58).

PALYNOLOGY OF THE ARNOT PIPE 61

Proteacidites sp. A Fig. 130-P

Description

Small, colpoidate pollen (as for example Beauprea elegans (Erdtman 1952: 343)) with triangular amb. Angulaperturate. The exine is intermediately thick, and thins at the margins of the colpi. Sexine thinner than nexine. Reticulate. Diameter of illustrated specimen 22 yp, exine 1,5 yp.

Proteacidites sp. B Fig. 13Q-R

Description

Small, triporate pollen with triangular amb; a rectangle with rounded corners in equatorial view. The pore is small and circular and the pore margins are simple. The exine is relatively thick, crassinexinous and reticulate. Diameter of illustrated specimen 20 w.

Affinity Pollens similar to Proteacidites sp. B are found in the Proteaceae and the genus Allophylus of the Sapindaceae.

Distribution

Proteacidites sp. B is rare at Arnot.

Genus Propylipollis Martin & Harris, 1974 Propylipollis meyeri sp. nov. 7 Fig. 14F-J

Etymology This species is named for A. P. and Christine Meyer of the farm Banke.

Description

Pollen triporate, angulaperturate, amb triangular, sides straight to slightly concave, apices roundly truncate. Exine relatively thick and crassinexinous. Nexine thickens as the pore is approached but is truncated before the pore in the sexine to form a post-atrium (sensu Kremp 1965, fig. 380); the state of preservation affects the visibility of this feature. Short radiating costae pori are present. Sexine reticulate. The reticulate pattern is irregular, angular and not always perfect and the size of lumina decreases towards the pores, so that in the vicinity of the pores a foveolate structure exists. Loose pieces of sexine may sometimes be present at the pore entrance. The coarseness of the reticulum varies

62 ANNALS OF THE SOUTH AFRICAN MUSEUM

considerably and two species may be present. The muri are mostly simplicolu- mellate, but in coarser areas duplicolumellate sections occur. The outline of the grain is smooth. Equatorial diameter 25—33 uw, exine 2 uw, pore 2—4 w, lumina approximately 1 w.

Affinity

The pollen of a number of genera of the subfamilies Grevilleoideae and Persoonioideae of the Proteaceae have similar pollen. The pollen of southern African species of Persoonioideae are not sufficiently well known to confirm a closer affinity, but affinities to the genera Lomatia and Leucospermum have been suggested (Germeraad et al. 1968).

Distribution

The species is common at Arnot. A related morphological form Proteacidites dehaani Germeraad, Hopping & Muller, 1968 is common in the uppermost Cretaceous and lowest Palaeocene strata of tropical Africa (Germeraad et al. 1968). The form is not present in late Cretaceous sediments off the south-western Cape coast (McLachlan & Pieterse 1978) A probably conspecific form occurs in the Neogene (?) Knysna lignites.

Propylipollis sp. Fig. 1SA-B

Description Triporate, the pores slightly protuberant and gaping. Angulaperturate. The amb is triangular and the shape oblate. The exine is thick and has a complex structure. Nexine, sexine and further subdivisions of the exine are clearly differentiated. The sexine is thick, atectate and irregularly foveolate. The grain is robust. Diameter of single specimen 44 w, pore 9-11 pw, exine 3-4 mw. Only one specimen was seen and the above description should be regarded as provisional.

Affinity The affinity of Propylipollis sp. is perhaps with the tribe Grevilleeae of the Grevilleoideae (Proteaceae) or with the Onagraceae.

Distribution

One specimen of Propylipollis sp. was observed at Arnot.

Tricolpate pollen Genus Tricolpites Cookson ex Couper, 1953 See discussion by Kemp & Harris (1977: 29).

Fig. 15.

PALYNOLOGY OF THE ARNOT PIPE 63

A-B. Propylipollis sp. C-—G. Tricolpites reticulatus. H-J. Spinitricolpites Jennerclarkei sp. nov.

64 ANNALS OF THE SOUTH AFRICAN MUSEUM

Tricolpites reticulatus Cookson, 1947 Fig. 15C-G

Tricolpites reticulata Cookson, 1947: 134, pl. 15 (fig. 45). Tricolpites waiparensis Couper, 1960: 66, pl. 11 (figs 13-15). Tricolpites reticulatus Cookson, 1947. Kemp & Harris, 1977: 30, pl. 5 (figs 1-2).

(See discussion by Kemp & Harris (1977) and Muller (1981: 67)).

Description

Tricolpate, fossaperturate; colpi short, extending about half-way to the poles. The grain is circular in equatorial view, the amb is lobate, and the whole surface is finely reticulate. The SEM photomicrographs illustrate the range of variation in morphology. In Figure 15F the amb 1s distinctly more lobate and fossaperturate, and the reticulate sculpture tends towards a tectate and foveolate state; despite a narrow size range, two species may be present. The margins of the colpi are marked by a flat seam in the sexine and a definite extension of the nexine beyond the sexine at that point and into the mouth of the aperture. This can be observed under both the light microscope and SEM. The grain is robust; equatorial diameter 19-26 w, polar diameter approximately 20 uw; exine clearly two-layered and approximately 1 mw; lumina 0,2—0,5 w.

Affinity

Tricolpites reticulatus is thought to have affinities with the genus Gunnera. According to the data provided by Jarzen (1980) the Banke forms are the smallest fossil Gunnera forms yet recorded, and closest—when compared to the average for extant pollen from certain geographical regions—to those of South America (acetolysed grains measured).

Distribution

Tricolpites reticulatus is common at Arnot, reaching a relative abundance of 7 per cent. It is known worldwide from the middle Cretaceous to the present and is often common. See Jarzen (1980) for a full discussion of the occurrence of Gunnera pollen in the fossil record as well as notes on the present-day habitat requirements and distribution of the genus. A single species Gunnera perpensa, a semi-aquatic species, is widespread in southern Africa except in South West Africa—Namiubia.

Tricolpites sp. A Fig. 16A-B

Description

Tricolpate; the amb is circular and the shape prolate. The colpi are long, thin, simple slits that stretch three-quarters of the polar axis of the grain. The exine is relatively thick and nexine and sexine are clearly differentiated. The sexine is columellate and tectate, and the columellae are intermediately robust. Dimensions 30-27 jw X 25-22 mw, exine approximately 1,5 w.

PALYNOLOGY OFRAHE ARNOT PIPE

Se SNE: OOS mess BZ

Fig. 16. A-B. Tricolpites sp. A. C-E. Crototricolpites densus. F-—G. Tricolpites sp. B. - H-I. Tricolpites sp. C. K-—M. Tricolpites sp. D.

65

66 ANNALS OF THE SOUTH AFRICAN MUSEUM

Affinity There is no information regarding the affinity of Tricolpites sp. A.

Distribution

This species was infrequent at Arnot.

Tricolpites sp. B Fig. 16F-G

Description

Tricolpate; the amb is triangular with convexly curved sides and angulapertu- rate. No specimen was observed in equatorial view, but it appears that its shape is _ biconvex. The colpi are very short, narrow slits. The exine is of intermediate height and the sculpturing is verrucate to dispersed rugulate, producing a negatively reticulate pattern.

Distribution

Tricolpites sp. B is rare at Arnot.

Tricolpites sp. C Fig. 16H-I

Description

Tricolpate; the amb is triangular with convexly curved sides and angulapertu- rate. No specimen was observed in equatorial view, but it appears that the shape is flat and very slightly biconvex. The colpi are very short, narrow slits. The exine is of intermediate width and granulate, and apparently thins in the immediate vicinity of the colpi to form an almost exineless rim of regular width around the colpi. Diameter of illustrated specimen 35 w.

Discussion

In the amb, position of the apertures and short, slit-like colpi there is some similarity between Tricolpites sp. B and Tricolpites sp. C. Only two grains of each were seen so that their descriptions must be regarded as provisional.

Affinity

There is a tenuous similarity between Tricolpites spp. B and C and the pollen of certain extant members of Protea such as P. mellifera or P. grandiflora (Erdtman 1952: 350).

Distribution

Tricolpites sp. C is rare at Arnot.

PALYNOLOGY OF THE ARNOT PIPE 67

Tricolpites sp. D Fig. 16K-M

Description

Tricolpate, amb circular to subcircular, shape oblate to biconvex. The colpi are of intermediate width at the equator, relatively long, and narrow to a point at their extremities. The exine is thick, and sexine and nexine are of similar width. The nexine forms a uniform dense layer, which broadens equatorially at the colpi margins to form marked costae endocolpi. This crassitude is apparently only present equatorially. The sexine is of regular width and curves over the nexine at the mouth of the colpi. The sculpturing is complex and coarse, and consists of an irregular granulate surface covered by micro-echinae. Equatorial diameter 43-45 pw, exine 2,5—4 wu, colpi width 2,5-4 wp.

Affinity

In form, size and the unusual surface sculpturing there is some resemblance between Tricolpites sp. D and the genus Ferocactus of the Cactaceae; see Ferocactus latispinus (Lozano-Garcia 1979: 310, pl. 6). However, present-day distribution and the established fossil record of the Cactaceae make this suggested affinity somewhat unlikely and forms similar to Tricolpites sp. D occur in a number of other families. The pollen is not similar to that of Rhipsalis, the only extant genus of Cactaceae that is possibly indigenous to Africa.

Distribution

Tricolpites sp. D is infrequent at Arnot.

Genus Crototricolpites Leidelmeyer, 1966 Crototrico.pites densus Salard-Cheboldaeff, 1978 Fig. 16C-E Crototricolpites densus Salard-Cheboldaeff, 1978: 224, pl. 1 (figs 10-12).

Description

The poilen grain is tricolpate, and almost circular in polar view. The grain is invariably flattened. The colpi are broad equatorially and have gaping, ragged margins; verrucae are the sculptural element and are angular, mostly triangular, in polar view. Their tops are pointed, with groups of five to six arranged in a circular pattern, the unit of a ‘croton pattern’. In polar view the colpus extends about one-half the diameter of the grain. The equatorial diameter is 34 uw, width of colpi at equator approximately 10 w, width of verrucae 1-2 yw, height of verrucae approximately 1 w.

68 ANNALS OF THE SOUTH AFRICAN MUSEUM

Discussion

The Banke specimens are similar to C. densus Salard-Cheboldaeff, 1978 and differ from C. annemariae Leidelmeyer, 1966, in the relatively smaller verrucae and circular ‘croton pattern’ units.

Affinity

The affinity of C. densus is with the Klaineanthus-type and perhaps, because of the doubtful feature of ragged colpi margins, with the Adenocline-subtype of the Crotonoideae of the Euphorbiaceae (Punt 1962).

Distribution

Crototricolpites densus is common at Arnot. The genus is known from the lower Eocene of Guyana and the Oligocene and lower Miocene of tropical Africa. Similar forms have not been recorded from Australia.

Genus Spinitricolpites gen. nov.

Diagnosis

Medium to large-sized, more or less spherical, tricolpate spiniferous pollen grains. The spines are medium-sized, with pointed or rounded tops and are sparsely and irregularly arranged on the sexine.

Type species Spinitricolpites jennerclarkei sp. nov. by original designation.

Etymology

The name refers to the spiniferous and tricolpate nature of the pollen grains.

Discussion

Apart from Tricolpites latispinosus McIntyre, 1965 (p. 207, figs 13-15) no similar forms have been encountered in the literature. The combination of large size, spherical shape, tricolpate state and spinate sculpturing would seem to justify the erection of a new genus. Spinitricolpites gen. nov. is here considered to include Spinitricolpites jennerclarkei sp. nov. and Tricolpites latispinosus McIntyre, 1965.

Spinitricolpites jennerclarkei sp. nov. Fig. 1SH-J

Etymology

The species is named after Mr Hugh Jenner-Clarke, an exploration geologist, who during many years work has located numerous kimberlite pipes in the Gamoep area.

PALYNOLOGY OF THE ARNOT PIPE 69

Description

The pollen grains are medium-sized, spherical to prolate spheroidal, tricolpate and spiniferous. The colpi are straight slits with no margo and are about one-half to two-thirds the polar diameter of the grains. In polar view the grain is circular but due to flattening the colpi are open at the equator. The margins of the colpi are not strengthened in any way and may appear frayed in polar view. The possibility that the grains are split rather than tricolpate can probably be excluded because of the regular positioning of the colpi in polar view and because the colpi can be seen in equatorial view. The spines are medium sized, mostly with pointed tips, and are sparsely and irregularly arranged on the surface of the grain; they sometimes occur in clumps or irregular rows. The exine is clearly differentiated into a sexine and nexine and the sexine is tectate, finely columellate and punctate. Equatorial diameter excluding spines 39-46 w, height of spines 3-5 pw, exine 1,5-2,5 w.

Discussion

The present form differs from S. latispinosus (McIntyre, 1965) in its longer, more sparsely distributed spines.

Affinity

There is no information regarding the affinity of S. jennerclarkei. In the large spherical shape and spinate sculpturing there is some resemblance to certain members of the Valerianaceae or Verbenaceae (Huang 1972).

Distribution

Spinitricolpites jennerclarkei is common at Arnot; S. latispinosus (McIntyre, 1965) is known from the Miocene of New Zealand.

Tricolporate pollen Genus Tricolporopollenites Pflug & Thomson, in Thomson & Pflug, 1953 Tricolporopollenites grandis sp. nov. Fig. 17K-N

Etymology

The specific name refers to the large size of the grain.

Description

The morphology of the pollen is complex. It is large, tricolporate, striate, ora lalongate or zonorate, highly prolate, ellipsoidal or with blunt ends. The colpi are narrow and extend almost to the poles. The exine is thick and a robust, striate sexine is clearly differentiated from the nexine. The nexine more than doubles its width as the lalongate endoporus is approached to form a costae endoporus, and the sexine thins in the small apocolpium. The striae are supported by wide

70

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Fig. 17. A-C. Tricolporopollenites brinkiae sp. nov. D-H. Tricolporopollenites arnotiensis sp. nov. K-—M. Tricolporopollenites grandis sp. nov. O-S. Tricolporopollenites sp. A.

PALYNOLOGY OF THE ARNOT PIPE Wil

columella and sections of muri of the same width, arranged in an irregular reticulate pattern that obscures the striate surface (which is so clearly visible in the purely topographic SEM photomicrograph (Fig. 17N)). There seems to be a centre line running length-wise down the middle of the mesocolpium, with a node on the equator around which the shallow curving pattern of the striae is centred. The colpi form a tangent to the arc of the striae with the position of the colporus being the point of intersection of the colpi and arc. Also, the elements of the striae are longest in the mesocolpium and apocolpium areas and are broken up into shorter elements in the vicinity of the colporus. Length of polar axis 45-56 pw, exine 2—5,5 w (including costae endopori), width of costae endopori 2,5-3,5 p, sexine approximately 2 uw, width of lalongate ora or pore zone 2-3 w.

Discussion

This is an unusual grain, which is not really comparable to any known fossil.

Affinity

In size, shape, general aperture type and the complex morphology of the sculpturing, the grain resembles the pollen of extant members of the genus Bauhinia of the Caesalpinaceae (Senesse 1980: 394).

Distribution

Tricolporopollenites grandis is common at Arnot.

Tricolporopollenites arnotiensis sp. nov. Fig. 17D-H

Etymology This species is named after the Arnot Pipe.

Description

Tricolporate, amb tending towards lobate, planaperturate grain. Subprolate in shape. The colpi are thin and about two-thirds the polar axis of the grain. The ora are lalongate, wider than the colpi and relatively long. Sexine and nexine are not always clearly differentiated, but the grain is crassisexinous. The sexine is tectate and finely columellate and there may be fine suprategillar sculpturing. Equatorial diameter 20—26 uw, polar diameter 20-24 w, ora width 1-2 w, exine 2 p, length of ora 6-7 w.

Affinity

There is some resemblance between 7. arnotiensis and the pollen of Anthospermum (Rubiaceae). Tricolporopollenites arnotiensis also resembles forms of the Euphorbiaceae with the Hippomane-configuration (Punt 1962), such as Euphorbia hypericifolia and E. heterochroma illustrated in Bonnefille & Riollet (1980, pls 47—48).

2: ANNALS OF THE SOUTH AFRICAN MUSEUM

Distribution

Tricolporopollenites arnotiensis is rare at Arnot. The extant genus Antho- spermum is found in Africa and Madagascar.

Tricolporopollenites brinkiae sp. nov. Fig. 17A—C

Etymology The species is named after Brink Scholtz.

Description

The grain is tricolporate and robust. In overall shape the amb is lobate. _ Fossaperturate. If, however, the sexine—which is very much thickened in the equatorial mesocolpium—1is excluded, the amb of the remainder of the grain is that of a very rounded triangle and the grain angulaperturate. In equatorial view the grain is oblate. The sexine and nexine are clearly differentiated and the prominent sexine is columellate, tectate and finely reticulate. The sexine thins abruptly in the vicinity of the colpi and then bends upwards to edge the colpi with distinct lips. The sexine is also thin in the apocolpium and the columellae are finer here than elsewhere. Equatorial diameter 24 uw, width of colpi 2-3 w, nexine approximately 0,5 uw, width of sexine in the mesocolpium 3 wp.

Discussion

Tricolporopollenites brinkiae has a very distinctive morphology and as far as is known no fossil species closely resembles it.

Affinity

This species bears some resemblance to the pollen of the southern African genus Nenax of the family Rubiaceae and, as with 7. arnotiensis, to certain Euphorbiaceae (cf. Euphorbia heterochroma—Bonnefille & Riollet (1980, pls 47—48)).

Distribution

Tricolporopollenites brinkiae is common at Arnot.

Tricolporopollenites coetzeeae sp. nov. Fig. 18I-L

Etymology

This species is named after Prof. J. A. Coetzee, who has done pioneering work on the Tertiary palynology of southern Africa.

PALYNOLOGY OF THE ARNOT PIPE

Fig. 18. A-B. Tricolporopollenites sp. C. C-F. Tricolporopollenites sp. D. G-H. Tricolporopollenites sp. B. I—L. Tricolporopollenites coetzeeae sp. nov. M-O. Forma H.

13

74 ANNALS OF THE SOUTH AFRICAN MUSEUM

Description

Large, tricolporate and verrucate grain. The exine is relatively thin and sexine and nexine layers are difficult to distinguish, except in the region of the thin costae endopori where the nexine is prominent. The verrucae are spherical and large relative to the exine. However, they are decorated with microconi that give them an angular appearance. The colpi are narrow and almost reach the poles of the grain. The ora are broad, lalongate and short and the costae endopori are marked. The amb is subcircular to lobate. The grain is prolate but due to the thin exine most specimens are deformed to some extent. Length 47—52 yu, width 30-34 w, exine 2-3 w including verrucae, width of ora 4-6 pw, length of ora 9-10 pw.

Affinity

In aperture morphology, size and general exine structure there is a similarity _ between this species and the pollen of the genus Zimmermania (subfamily Phyllanthoideae of the Euphorbiaceae) (Punt 1962: 29, pl. 4 (fig. 1)). However, the prolate shape of T. coetzeeae, as well as the close packing of the verrucae and their decoration with microconi, is a condition not approached by the pollen of any of the seven extant species of Zimmermania. The fossil form is most similar to the pollen of the species Z. acuminata, Z. ovata and Z. capillipes (Poole 1981).

Distribution

Tricolporopollenites coetzeeae is infrequent at Arnot. The genus Zimmer- mania is endemic to East African montane areas, where it occurs mainly in mist forests (Poole 1981).

Tricolporopollenites sp. A Fig. 170-S

Description

The pollen is tricolporate, the shape prolate to pointed oval, fossaperturate and striate, the amb is circular. The colpi are fairly deep and wide, and narrow towards the poles. The ora are lalongate and pinched at the transection with the colpi. There are marked costae pori. The striae are simplicolumellate. Equatorial diameter of illustrated specimen 23 w, polar diameter 32 w.

Affinity The affinity of Tricolporopollenites sp. A is probably with the genus Rhus of the Anacardiaceae.

Distribution

The earliest records of pollen of the Rhus-type are from the Maastrichtian of North America and upper Palaeocene of Europe. It has not been reported from

PALYNOLOGY OF THE ARNOT PIPE 1S

the early Tertiary of Australia and is not present in Maastrichtian sediments of southern Africa (McLachlan & Pieterse 1978). It is present in the late Neogene of central Africa (Sah 1967) and the Neogene (?) Knysna lignites. Members of the Anacardiaceae are known from the Eocene of tropical Africa.

Tricolporopollenites sp. B Fig. 18G—H

Description

Tricolporate, amb circular and shape ellipsoidal. The exine is of medium thickness and sexine and nexine are clearly differentiated. Crassinexinous. The sexine is tectate, finely columellate and granular. The colpi are narrow and almost reach the poles of the grain. The ora are lalongate, slit-like and of medium length and the costae endopori are robust. Length of illustrated specimen 27 pw, width 21 w, width of ora approximately 0,5 w, length 3 wp.

Discussion

The slit-like ora is a characteristic feature of Tricolporopollenites sp. B.

Affinity There is no information regarding the affinity of Tricolporopollenites sp. B.

Distribution

This species was infrequent at Arnot.

Tricolporopollenites spp. C and D Species C: Fig. 18A—B; Species D: Fig. 18C—F

Description

Both species are small and angulaperturate grains. Tricolporopollenites sp. D has a more triangular amb than Tricolporopollenites sp. C, and both are prolate. The surface sculpturing of the two forms also differs. The colpi are narrow and almost reach the poles. They are deeply buried in narrow clefts shaped by the sharp inward bends in the exine at the apices of the triangular amb. The ora is small and protrudes into this cleft producing the characteristic ‘H-shape’ seen in equatorial view. The exine is thick and finely columellate. Length of polar axis 18-25 w, width 13-18 w, exine approximately 2 wp.

Affinity

Ferguson (1977) has described ‘H-shaped’ aperture structures in certain genera of the Cornaceae. These structures are formed by a pore being joined to two lateral thinnings of the endexine that run parallel to the colpus. The fossil types described above probably possess this structure. If the uniqueness of this

76 ANNALS OF THE SOUTH AFRICAN MUSEUM

aperture morphology is confirmed, these fossils represent the first certain, and by far the earliest, record of cornaceous pollen to date. The particular genus concerned is Cornus and the Cornus sanguinea-subtype (Ferguson 1977: 6, figs 31, 4f-g, 5a-g). The fossil forms are unlike the pollen of Curtisia, the extant monotypic southern African genus of the Cornaceae. Ferguson (pers. comm. 12 July 1984) notes that similar endoapertures also occur in at least one genus of the Rubiaceae (Lewis 1965) and in various genera of the Escalloniaceae and Penthoraceae, and in the genus Sedum of the Crassulaceae. The occurrence of this feature is discussed in Hideux & Ferguson (1976).

Distribution

Both species are rare at Arnot.

Pollen with more than three apertures Genus Retistephanocolpites Leidelmeyer, 1966

See Saxena (1982) for a discussion of this genus.

Retistephanocolpites sp. Fig. 19E-G

Description

The pollen is tetracolpate. The colpi are about two-thirds the polar axis, wide open at the equator and their margins are entire. The exine is relatively thick, crassisexinous and tectate. The tectum is closed and columellate, and under the SEM it can be seen that the surface sculpturing consists of a dense mat of fine strands. The amb is circular. Diameter 16-20 pw, exine 1,5 w.

Discussion

See Saxena (1982) for a detailed discussion of the taxonomy of Tertiary polycolpate forms. Many of these forms are known especially from the Indian Tertiary record. As Saxena points out, exinal thickenings and precise sculptural details are conservative features that are of the most use in attributing generic status to fossil forms and suggesting their affinities. The unusual surface morphology of the present form should lead to eventual positive identification.

Affinity No positive suggestions can be made regarding the affinity of Retistephano-

colpites sp. The pollen of Rubia (Rubiaceae) and Catostemma (Bombaceae), amongst others, appear superficially similar to this fossil species.

Distribution

This form is rare in levels sampled at Arnot but it is the dominant angiosperm pollen in earlier (early Palaeocene?) sediments from Namaqualand.

PALYNOLOGY OF THE ARNOT PIPE

ee ee es

qd

Fig. 19. A-B. Grootipollis reuningii sp. nov. C-D. Crotonipollis burdwanensis.

E-G. Retistephanocolpites sp. H. Ulmipollenites sp. 1-J. Forma G. K-L. Forma F.

78 ANNALS OF THE SOUTH AFRICAN MUSEUM

Genus Grootipollis Krutzsch, 1966 Grootipollis reuningti sp. nov. Fig. 19A-B

Etymology

This species is named after Dr E. Reuning, the geologist whose interest in the Arnot Pipe, Banke, led to the discovery and study of its fossiliferous sediments.

Description

The pollen is spherical and always invaginated to some degree. It is periporate and has between fourteen and twenty pores. Triangular-shaped verrucae of medium height, with rounded tops, are arranged in circular ‘croton _ patterns’. Five to eight verrucae, each with an apex pointing towards the middle, form a single circle, but this pattern is disrupted where a pore is situated. The verrucae are quite small structures so that their triangular shape may not readily be noticed in plan view. The exine is thick. Equatorial diameter 45—50 w, exine approximately 3, size of verrucae (plan view) 1m, diameter of pore approximately 3 w.

Discussion

Grootipollis reuningii is twice the size of the type species of the genus, Grootipollis cretacius (Jansonius & Hills 1976: 1191), which also has relatively smaller and fewer pores (8-10 in G. cretacius versus 14—20 in G. reuningii). Apart from the obvious differences in aperture morphology, the smaller verrucae and circular arrangement distinguish G. reuningii from the two other forms displaying the ‘croton pattern’—Crototricolpites densus (see p. 67) and Crotonipollis burdwanensis (see p. 80), which occur at Arnot.

Affinity

Grootipollis reuningii shows affinity with genera of the Thymelaeaceae (such as Phaleria, Passerina and Struthiola) and to the Buxaceae (Muller 1981: 48). The former is considered the more likely.

Distribution

Grootipollis reuningii is common at Arnot. The genus and related forms are known from the late Cretaceous of the Northern Hemisphere (Muller 1981: 48), but have not been recorded from Australian late Cretaceous or Tertiary sediments.

Genus Ulmipollenites Wolff, 1934

See Srivastava (1969) for discussion on this genus.

PALYNOLOGY OF THE ARNOT PIPE 79

Ulmipollenites sp.

Fig. 19H

Description

Medium-sized, 5-colpate, aspidote form. The exine is relatively thick and the aspides, around the short narrow colpi, appear as prominent knobs. The exine appears undifferentiated under the light microscope and the surface sculpturing is undulating to rugose. Diameter of illustrated specimen 24 yw, exine 1,5—2 w, exine at aspides 3 yw, colpi width 0,75 yu.

Discussion

The present form differs slightly from available descriptions of other fossil forms placed in the genus U/mipollenites and the related genus Ul/moidipites in the degree of narrowness of the colpus pore and the degree of thickening of the aspides. In other respects it is similar to extant species of Ulmus such as U. glabra (Nilsson et al. 1977: 108). However, Ulmipollenites sp. is also similar to the species Haloragis haloragoides (Cookson & Pike, 1953), suggesting a possible affinity to Haloragis (Haloragidaceae) (H. A. Martin 1973: 21). More specimens will have to be studied before the correct affinity of this form can be determined.

Affinity The affinities of Ulmipollenites sp. are thought to be with the genus U/mus of the Ulmaceae or with members of the Haloragidaceae.

Distribution

This species is rare at Arnot. Ulmus-like pollen appears over a widespread area including Africa, North and South America and India during the Maastrichtian (Muller 1981: 19; Salard-Cheboldaeff 1981). In West Africa the form has a continuous record up to the Miocene. Haloragis- or Haloragicidites- types are known from the Eocene of Eurasia (Muller 1981) and the Miocene in Australia (H. A. Martin 1973).

Inaperturate pollen

Genus Crotonipollis Baksi, Deb & Siddhanta, 1979

The above name is used here despite the fact that Baksi et al. (1979) instituted their genus apparently unaware of a prior homonymous generic diagnosis with a very different content (De Lima 1976).

80 ANNALS OF THE SOUTH AFRICAN MUSEUM

Crotonipollis burdwanensis Baksi, Deb & Siddhanta, 1979 Fig. 19C-D Crotonipollis burdwanensis Baksi, Deb & Siddhanta, 1979: 233, fig. 1.

Description

The grain is large, robust and inaperturate and the sexine bears large regular-shaped, triangular verrucae arranged in the characteristic ‘croton pattern’. Six triangular verrucae, each with an apex pointing towards the middle, constitute a unit of the ‘croton pattern’. The grain is so robust that under the light microscope and normal processing no details of the nexine can be distinguished. Diameter 50 w.

Discussion

Baksi et al. (1979) discuss the differences between two Indian species of Crotonipollis.

Affinity

Baksi et al. (1979) mention the similarity between Crotonipollis and the pollen of extant species of Jatropha (Euphorbiaceae). A large number of genera of the subfamily Crotonoideae are listed by Punt (1962) as possessing the inaperturate ‘croton’-type pollen, so that determination of closer affinities within this group must await further work. At least some species of Jatropha have prominently ‘ribbed’ verrucae (Bonnefille & Riollet 1980: 69, pl. 52) and thus clearly differ from the present forms. The genus Croton is a more likely affinity—cf. Croton draco (Lonzano-Garcia 1979: 318, pl. 12).

Distribution

Crotonipollis burdwanensis is rare at Arnot. It also has rare and restricted occurrence in the Eocene and Palaeocene of India.

Pollen found in obligate tetrads Genus Ericipites Wodehouse, 1933 Ericipites sp. A Fig. 20A—C

Description

Tetrahedral tetrads of tricolporate pollen with hamulate to weakly rugulate sculpture. The amb of each monad is subcircular. The exine is relatively thin. Apertures arranged according to Fischer’s rule (Erdtman 1952: 14); the colpi are long thin slits, which broaden equatorially to enclose the ora. Ora lalongate. The costae endopori are prominent. Colpi are three-quarters to two-thirds the length of polar axis. Diameter of tetrad 24-35 mw, exine 1-1,5 wp.

81

PALYNOLOGY OF THE ARNOT PIPE

G. Dicotetradites sp.

Fig. 20. A-C. Ericipites sp. A. D-E. Ericipites sp. B. F-

H-M. Triporotetradites sphericus sp. nov. N. Dicotetradites sp.

82 ANNALS OF THE SOUTH AFRICAN MUSEUM

Ericipites sp. B Fig. 20D-E

Description

Tetrahedral tetrads of tricolporate pollen. The colpi are thin slits and relatively short and the ora are inconspicuous. Apertures are arranged according to Fischer’s rule (Erdtman 1952: 14). The amb is subcircular to triangular with broadly rounded apices. The nexine is robust and the sexine is fossulate, being traversed by fine cracks.

Affinity

As Martin (1978) and others have pointed out, the tetrads of the Ericaceae, Empetraceae, and Epacridaceae can generally not be distinguished. The extant families are also not well known palynologically. Because of the distribution of the modern families it is likely that the present forms have affinity to the Ericaceae and, less likely, to the Epacridaceae.

Distribution

The earliest record of tetrads with Ericipites-like morphology may be from marine middle Cretaceous sediments off North Africa (Kotova 1978). Forms designated Ervicipites are first recorded in the Northern Hemisphere in European Maastrichtian sediments and may have affinity to the Ericaceae or Empetraceae (Muller 1981: 41). By the Eocene they can be a common element in assemblages from central Europe (Muller 1981). An Ericipites form, Ericipites scabratus (Harris, 1965), comparable to Evicipites sp. A above, is an infrequent element in middle to late Palaeocene sediments from south-eastern Australia (Harris 1965) and a further form, Ericipites crassiexinous, is common in middle to upper Eocene strata. Ervicipites was not recorded in Maastrichtian sediments off southern Africa (McLachlan & Pieterse 1978) nor, for some peculiar reason, was it observed in the Neogene (?) Knysna lignites (Thiergart et al. 1963). It is a component of the late Neogene record in the south-western Cape (Coetzee 1981).

Ericipites sp. A is relatively common at Arnot while Ericipites sp. B is rare. This is the earliest record from the African subcontinent of a plant group that is a prominent member of the Capensis Flora today.

Genus Dicotetradites Couper, 1953 Dicotetradites sp. Fig. 20F—G, N Compare

Dicotetradites clavatus Couper, 1953: 63, pl. 8 (fig. 125). Paripollis ochesis Partridge, in Stover & Partridge, 1973: 274, pl. 28 (fig. 2).

PALYNOLOGY OF THE ARNOT PIPE 83

Description

The pollen occurs in obligate tetrads. It could not be ascertained whether the monads are tricolpate or tricolporate, but the colpi are long and arranged in the normal manner according to Fischer’s rule (Erdtman 1952: 14). The ora, if indeed present, are inconspicuous and opposite one another. The robust clavae contribute towards the difficulty of observing the ora. Each monad is subspherical to subtriangular; the exine is thick and clearly differentiated into a nexine and sexine. The nexine broadens to end in a knob at the margins of the colpus. The sexine is decorated with robust verrucae or clavae which are angular in plan and have rounded tops. These structural elements are most robust in the distal polar region and become smaller in the equatorial region. The sexine is hardly, if at all, present on the interfacial proximal face of each monad. Overall size very variable. Diameter of figured specimen 45 yw, diameter of monads 30-33 yw, exine 6 pw in the distal polar area, 3 yw in the equatorial area.

Discussion

Only five specimens were observed and the overall size range and variation in sculpturing suggest that more than one species is present. Figure 20N shows a grain tending towards the clavate-baculate condition described as Dicotetradites clavatus Couper, 1953, while the well-preserved grain illustrated in Figure 20F—G is very similar to Paripollis ochesis Partridge, in Stover & Partridge, 1973. Because of the uncertainty as to whether the present form has an ora or not, the original generic diagnosis Dicotetradites was provisionally preferred and the revised diagnosis of Crosbie & Clowes (1980) was ignored.

Affinity

The affinity of Dicotetradites sp. is probably with the Epacridaceae, which also have obligate tetrad forms with individual grains possessing verrucate sculpturing that may obscure their apertures, and with the sexine confined to their distal walls and absent from the contiguous proximal walls (Mathews 1966: 464, 469, pl. 2 (fig. 3)—cf. Epacris heteronema).

Distribution

Dicotetradites sp. is very rare at Arnot. The genus Dicotetradites is a common form in the Eocene of New Zealand with a range from the Palaeocene to the late Oligocene (Crosbie & Clowes 1980: 460). It is also known from the Oligocene in south-eastern Australian sediments (Stover & Partridge 1973). Similar forms have not been reported from the Northern Hemisphere or tropical Africa. Today the Epacridaceae are found mainly in Australia and Tasmania, but also in South America (Willis 1966).

84 ANNALS OF THE SOUTH AFRICAN MUSEUM

Genus Triporotetradites van Hoeken-Klinkenberg, 1964 Triporotetradites sphericus sp. nov.

Fig. 20H-M

Etymology

This specific name refers to the spherical shape of the tetrad.

Description

The structure of the grain is extraordinary. It is a tetrad with each monad so shaped that the whole grain is spherical. It could be described as a spherical, cross tetrad with all four monads meeting at the centre. Each monad is triporate, the pores being circular and arranged according to Garside’s rule, i.e. three pores grouped together at four points on the surface of the grain (Erdtman 1952: 14). The wall of each monad is psilate and is not differentiated under the light microscope; the pore structure in this layer consists of a low, narrow but distinct ring on the exterior of the grain, which forms the top rim of an elongated chimney extending into the interior of the monad. Each group of pores is situated in the hollow beneath the sexinal (?) layer formed by the curving of three adjacent monads away from the circumference of the tetrad. The rims of the three adjacent pores may touch one another. The four monads are enveloped by a reticulate, simplicolumellate, undifferentiated sexinal (?) layer to form a single inaperturate spherical grain. The reticulum is regular and perfect and the sexine may thicken over the groups of pores. The size of the grains is very uniform, the diameter of all measured specimens being between 31 and 34 yw, sexine varies between 1,5 and 3,5 w, diameter of pore opening 1,5-3 pw, height of whole pore structure 4—5 p, size of lumina approximately 1 wp.

Discussion

Triporotetradites sphericus can be distinguished from Bysmapollis emaciatus Partridge, in Stover & Partridge, 1973 (p. 273, pl. 28 (fig. 1)) in pore and exine structure; the latter also has pores arranged according to Garside’s rule (Erdtman 1952: 14) The inaperturate, enveloping, reticulate layer of T. sphericus is the most distinguishing feature. The only other tetrad that has pores arranged similarly is Ajatipollis tetraedralis (Bolkhovitina) Krutzsch, 1970. In this form, however, the pore placement is described as free, and the pores are clearly not as closely grouped as in the present form. Crosbie & Clowes (1980: 460, figs 4, 6) note that tetrads of the species Dicotetradites clavatus Couper, 1953, have a granulate sexinal layer which is continuous over the junction of individual grains.

Figure 20L—M shows a grain with some of the reticulum missing and with the psilate nexine (?) of the individual grains, as well as their pore structure, exposed. It is likely that a new genus will eventually have to be erected to contain this form.

PALYNOLOGY OF THE ARNOT PIPE 85

Affinity

It has been suggested that members of the genus Triporotetradites have affinity with the extant genus Gardenia of the Rubiaceae. Triporotetradites sphericus, however, differs widely from any known Triporotetradites.

Distribution

The present form is common at Arnot. The genus 7riporotetradites is known from the upper Eocene of Europe and the lower Miocene of the Cameroons (Muller 1981). Muller regards a Maastrichtian record of the genus from Nigeria (Van Hoeken-Klinkenberg 1964) as not acceptable. Stover & Evans (1973: 58) mention an undescribed Triporopollenites type and illustrate a ‘planar tetrad’ that superficially resembles the present form. These forms occur in late Cretaceous and Palaeocene sediments of the Gippsland Basin, south-eastern Australia.

Dicotyledonous pollens not assigned to genus Forma F Fig. 19K-L

Description

Large, thin-exined 5-colpate form with a circular amb. The colpi gape equatorially and have characteristically rounded ends. Nexine and sexine are differentiated and the exine is subpsilate. Diameter of illustrated specimen 34 wp.

Affinity The affinity of Forma F is perhaps with the Labiatae.

Distribution

Forma F is rare at Banke.

Forma G Fig. 19I-J

Description

Tricolporate, very rounded triangular, planaperturate, crassiexinous, psilate grain. Crassiendexinous. The ektexine stops short of the colpus as the endexine thickens to form a low costae colpus. Regarding the intectate sexine the grain is syncolpate. The endocolpus is lalongate. Equatorial diameter 25 mw, exine 2,5 wu, endexinous costae colpus 4 w thick.

Discussion

Forma Gis a rather unusual grain with no comparable fossil forms known. In the very thick exine and syncolpate state there is some similarity with the following form.

86 ANNALS OF THE SOUTH AFRICAN MUSEUM

Affinity The affinity of Forma G is unknown.

Distribution

Only one well-preserved grain was observed at Arnot.

Forma H Fig. 13M—O

Description

The grain is tricolpate and crassiexinous. A thin ektexine may be present but can hardly be differentiated from a massive endexine. At one pole the grain is apparently syncolpate, the exine thinning towards this pole. There is some irregularity in the margins of the colpus and a suggestion of a hexaporate condition with the two pores of each colpus situated non-symmetrically around the equator. The amb is lobate and the shape is oblate but with a clear irregularity, the exine thinning towards the syncolpate pole. Equatorial diameter of illustrated specimen 29 yw, exine 4 w, colpus 2 wu wide, polar axis 22 p.

Discussion

Forma H is a highly unusual grain especially in its lack of symmetry.

Affinity

There would seem to be little resemblance between Forma H and any extant family except perhaps (but excluding the lack of symmetry) to the Gyrostemon- aceae (Erdtman 1952: 198).

Distribution

Only one well-preserved grain was observed.

Forma I Fig. 21A-B

Description

Only two specimens were observed and the following description is preliminary. A medium-sized, probably tricolporate grain with an open reticulate sculpturing developing into longitudinally striate sculpturing in the area of the colpi fossae.

Discussion

As far as is known, no very similar fossil forms are known. The reticulate sculpturing illustrated in Figure 21B resembles Alangiopollis eocaenicus as illustrated in Reitsma (1970: 283, pl. 33).

PALYNOLOGY OF THE ARNOT PIPE

F

Fig. 21. A-B. Formal. C-F. Fenestriorites (photomicrographs not of material from Arnot).

87

88 ANNALS OF THE SOUTH AFRICAN MUSEUM

Affinity

The affinity of Forma I is possibly with the Alangium kurzii-type of the Alangiaceae, Section Marlea, as described by Reitsma (1970). If this is correct then, although Forma I is a new specific record, the pattern that all early fossil occurrences of this family are of the primitive Section Marlea is maintained.

Distribution

Forma I is rare at Arnot. Alangium kurzii and A. rotundifolium are found today in forests of Indo-China.

POLLEN COUNTS

The pollen diagram (Fig. 3A) expresses the value of individual elements as percentages of the total number of grains counted for each of the seven sampled levels. Only values of one per cent and greater are included.

Little can be deduced from the pattern revealed by the diagram. Triorites operculatus is always the most common form. A sharp increase in its relative abundance occurs towards the top of the diagram where it achieves values greater than 40 per cent. This increase does not correlate with simultaneous changes in abundance of any other elements, but is preceded by a sharp increase in the abundance of Stereisporites (Sphagnum) and the other spores. These last two elements clearly covary. A likely explanation for this peak in their abundance is that some change in the local geography allowed greater run-off and water trans- port to the depositional environment. The sample from 20-21 m (65-70 feet) is not highly carbonaceous so that the immediate presence of a peat bog is not indicated. The increase of Stereisporites together with the other spores (which include two possible tree-ferns— Cyathidites and a member of the Lophosori- aceae) suggests that all grew in the same environment. This may have been a forest with the plants concerned growing either on the floor (moss) or as part of the understorey (tree-ferns and other ferns).

The occasional peaks in the abundance of Clavatipollenites, Triorites arnotiensis and Tricolporopollenites brinkiae may represent changes in local edaphic conditions and/or a slight shift in a vegetation boundary. Some extant genera of Chloranthaceae (represented at Arnot by Clavatipollenites) are forest- margin species. The coherent patterning in the percentage values of Triorites operculatus and Dicolpopollis sp. are possibly indicative of long-term change in the regional vegetation and there is some basis for speculation on its nature (see point 21 of the discussion).

The percentage values for conifers varied between 15 and 5 per cent.

DISCUSSION

The body of this research has consisted of systematic, descriptive palynology. The affinity of as many fossil forms as was possible has been noted and the results of this work are summarized in point form below. The detail achieved allows for

PALYNOLOGY OF THE ARNOT PIPE 89

some comparisons to be drawn with the Australian and tropical African early Tertiary palynomorph records, and some statistics to be produced on the taxonomic levels and degree of extinction that has occurred in Africa between the early Tertiary and the present.

The described assemblages from Arnot are isolated in time and space. Although subsequent work has provided more biostratigraphic evidence, long continuous sequences and a stable dating framework are not yet available. The fact that only seven samples from a short 25 m sequence could be analysed makes it difficult to evaluate the changes recorded.

The small amount of work done on palynomorph assemblages from kimberlite pipes from the northern Cape and from Botswana and the general paucity of published work on local late Cretaceous and Tertiary palynology make discussion on vegetation history in these time ranges on the subcontinent premature. However, the evidence produced in this study provides a much better base than was previously available for tentative statements regarding the vegetation represented at Arnot and the palaeoclimate involved. Furthermore, since other authors (Axelrod & Raven 1978; Tankard & Rogers 1978) have placed their interpretations upon the previously published palaeobotanical evidence from Arnot, it was thought that some remarks on these subjects were necessary.

Some of these remarks rely upon suggested features of the local and regional geography of the site and its mechanism as a pollen trap for their support. These features (see p. 5) may be summarized as follows:

The regional topography was that of a relatively mature, flat landscape unassociated with any prominent montane region. The country rock of the area is Namaqualand gneiss, which was blanketed by base rich ‘kimberlitic’ material in the vicinity of the Arnot Pipe. The cones of ejectamenta of the numerous ‘kimberlite’ volcanoes are thought to have been relatively low (perhaps in the order of 100—150 m) and the infilling of each crater to have been completed a few million years (maximum) after emplacement. The crater lake formed in the vent of the palaeo-Arnot Pipe volcano accumulated laminated, fine-grained, carbon- aceous shale and mudstone sediments towards its centre and acted as a local, small basin pollen trap, unrelated to developed drainage patterns. The agents of pollen transport would have been wind, local run-off, and probably settling out of suspension of fine sediments and pollen in the quiet centre of the lake after gravity avalanching of material off the talus slope of the cone.

Although the slopes of the volcanic cones must have provided special edaphic conditions favouring certain plant species, these areas were isolated features in the general landscape. Even the plants that occurred on the local edaphic site would have formed part of a more generalized, wider distribution of plant associations. There is no climatological reason to suppose that the Palaeo- cene location of the region experienced a transition zone between climatic regimes.

In terms of the present knowledge available, therefore, it seems safe to suggest that the species of plants recorded at Arnot grew on base rich soils and

90 ANNALS OF THE SOUTH AFRICAN MUSEUM

were part of a widespread non-montane Palaeocene vegetation growing in the interior of the subcontinent.

1. The following plant familes are represented in the Arnot palynoflora: (a) Pteridophyta and Bryophyta: Sphagnaceae, Cyatheaceae, Anthocerotaceae, Polypodiaceae, Schizaeaceae and Ophioglossaceae. (b) Conifers: Podocarpaceae and Araucariaceae. (c) Angiosperms: Chloranthaceae, Restionaceae, Palmae, Ulmaceae (UI- moideae) or Haloragidaceae (?), Casuarinaceae or Myricaceae, Proteaceae, Gunneraceae, Euphorbiaceae, Thymelaeaceae, Anacardiaceae, Cornaceae, Eri- caceae, Epacridaceae and Caesalpinaceae.

Several more tentative suggestions about the possible affinity of fossil morphotypes to modern families are also made in the text.

2. The lack of diversity in the families Proteaceae, Ericaceae and Res- ‘tionaceae is notable. These three families are at present large and prominent components of Cape fynbos vegetation. By Eocene times the Proteaeceae are highly diversified in Australia (Martin 1981) and are represented by many forms in the Knysna lignites (Thiergart et al. 1963), which may be either Eocene— Oligocene (Thiergart et al. 1963; Helgren & Butzer 1977), or early Neogene in age. Both subfamilies of the Proteaceae, the Persoonioideae and Grevilleoideae, may be represented in the Arnot assemblages but no proteaceous form is common to the Arnot and Australian early Tertiary assemblages. Most of the proteaceous forms probably represent extinct genera, but the genera Leucosper- mum and Protea may be represented. The evidence from the pollen morphology of the Restionaceae suggests that present ideas about evolution within this family may need revision (see Johnson & Briggs 1981).

3. The diversity in the Euphorbiaceae (non-heathland types, Specht 1981: 790) is notable. The evidence for early presence in the African subcontinent of species with affinity to the Euphorbiaceae, Thymelaeaceae, Monimiaceae, Anacardiaceae, Rubiaceae (?) and Ulmaceae (?), amongst others, is also important and provides valuable data for a perspective on the in situ evolution of plant phylogenies in the subcontinent. Wood of Euphorbiaceae and Monimiaceae has been identified in late Cretaceous deposits on the east coast of southern Africa (Miiller-Stoll & Madel 1962).

4. In terms of biostratigraphic age-bracketing, none of the evidence contradicts a possible Palaeocene date for the sequence. The assemblage is composed of a mixture of: (a) forms whose affinity to modern families can be traced, and (b) archaic forms known mainly from, or with a record extending back into, the Cretaceous. This combination suggests proximity to the Cre- taceous—Tertiary boundary (see points 5 and 6 below). On the other hand Monoporites annulatus (Gramineae) while prominent in tropical African Eocene assemblages (Salard-Cheboldaeff 1979, 1981) does not occur at Arnot. This may support a pre-Eocene age for these assemblages.

PALYNOLOGY OF THE ARNOT PIPE 91

5. The following form-genera and species present at Arnot are known mainly from the Cretaceous:

Araucariacites sp., Zonalapollenites, Monocolpopollenites, Fenestriorites, Ali- sporites grandis, Foveotriletes margaritae, Cicatricososporites, Distaverrusporites and Hamulatisporis.

In addition Arecipites, Liliacidites, Tricolpites reticulatus and Clavatipollen- ites forms are common in the late Cretaceous but continue through the Tertiary, and Araucariacites australis exits from the tropical African record in the late Cretaceous and from the Indian record at the Cretaceous—Tertiary boundary, but has a continuous record into the Tertiary in Australia.

6. Comparing the Arnot palynomorph assemblage with other Palaeocene assemblages* and with extant floras produces the following rough estimates: (a) 57 per cent of the species are unique to the Palaeocene of the African subcontinent; (6) 59 per cent no longer occur in Africa; (c) 39 per cent are extinct; (d) 39 per cent of the forms, and (e) 60 per cent of the families, are common to the Arnot and south-eastern Australian Palaeocene, while only (f) 12 per cent of the forms, but (g) 65 per cent of the families, are common to the Arnot and tropical African Palaeocene. (a—d excluding pteridophytes, no families of which are known to have become extinct during the Cenozoic.)

These statistics are employed in the discussion that follows.

7. At generic levels (refer to 6e above) the Arnot Palaeocene flora is more closely related to south-eastern Australian than to tropical African Palaeocene floras. This reflects in the main a common southern Gondwana pteridophyte and conifer floral inheritance. However, a degree of similarity in the climates of the two regions is also indicated. The low level of commonality at generic rank (6a, f) between the Arnot and tropical African assemblage suggests a marked difference in the climates experienced in the two regions. This pattern is superimposed upon a continuing phytogeographical relationship expressed at a higher taxonomic level (see 6g). The uniqueness (see 6a) of the Arnot flora mainly emphasizes its difference from the tropical African Palaeocene flora.

Points 6b and 6c are measures of the antiquity of Palaeocene floras and although comparable estimates are not available, a rough comparison does suggest that the level of ‘modernity’ encountered in south-eastern Australian Palaeocene flora might be similar to that of the Arnot flora and dissimilar to the state of the tropical African Palaeocene flora. It would appear from the work of Salard-Cheboldaeff (1978, 1979, 1981) that this latter flora contains many archaic

* The studies on which these comparisons are based include Germeraad et al. (1968), Salard-

Cheboldaeff (1978, 1979, 1981), Martin (1978, 1981), Harris (1965), Kemp & Harris (1977), Kemp (1981), Stover & Partridge (1973), and Muller (1981).

92 ANNALS OF THE SOUTH AFRICAN MUSEUM

forms and that, in the equatorial region, continuity with Neogene floras is only marked from the Upper Eocene—Oligocene (Salard-Cheboldaeff 1981: 435).

The difference of 20 per cent between 6b and 6c is a measure of the level of extinction that has occurred in Africa between the Palaeocene and the present. It suggests the contrast in this continent between the Palaeocene environment— with perhaps more equable climates and easy transitions between climates—and the subsequent global development of more distinct zones of climate and vegetation, some of which were not well represented in Africa. In particular, Africa does not extend into high southern latitudes and therefore lacks an extensive zone of temperate climate and the role that this might play on a continental scale in the evolution of vegetation. For this reason, in addition to the probable relative aridity of Africa in the Cenozoic, the subtropical—temperate vegetation of Africa has suffered a relatively high degree of extinction between the Palaeocene and the present.

8. The connections and contrasts of the Arnot palynoflora with early

Tertiary south-eastern Australian floras can be further elucidated. (a) The low percentage representation of spores at Arnot relative to the Australian norm (5% versus 20-30%) may be explained either by reference to the general pattern of low spore representation in Africa (Salard-Cheboldaeff 1981) or by the peculiar geographic setting of the Arnot site. Relevant to the former explanation are the suggestions that Africa has been relatively drier than Australia for a long time and/or that the pattern reflects the intracontinental location of the sites producing this pattern, i.e. east coast of Australia, west coast and interior of Africa.

The latter explanation suggests that whereas it can be assumed that most spores reach a depositional environment via water transport, this agent of transport (as already indicated, see p. 88) may have played a minor role in the geographical setting of the Arnot Pipe. Although involving an obviously circular argument, there is some support in the covariation of values for Stereisporites and the other spores for the suggestion that an increase in water transport explains the single anomalously high value of 20 per cent recorded for these two elements at the 65-70 foot (20-21 m) level (see Fig. 3).

(b) Apart from relatively high spore representation (indicating high humidity and/or equability), the south-eastern Australian conifer flora is dominated by podocarpaceous taxa, especially the genera Dacrydium and Microcachrys. In contrast Araucariaceae entirely dominate earlier Palaeocene or late Cretaceous assemblages from the Arnot region and make up about half of the conifer representation at Arnot. This contrast is explained by the comparatively high latitude of south-eastern Australia in the Palaeocene (65°S versus 40°S today) and the correspondingly lower temperatures and more temperate climate experienced there.

However, Araucariacites is hardly represented at all at a more northerly and inland Australian site situated at about 50°S in the same time range (Wopfner et al. 1974).

PALYNOLOGY OF THE ARNOT PIPE 93

Although the non-occurrence of a form at a particular site is not a reliable observation, it is to be noted in comparing the Palaeocene Australian conifer flora with the Arnot flora that Microcachryidites, Dacrycarpus, Dacrydium franklinii- type, and Phyllocladus are not recorded at Arnot. All of these forms, however, except the Dacrydium franklinii-type and the Dacrydium cupressinum-type (recorded at Arnot) are known to occur in the late Cretaceous in the south- western Cape (McLachlan & Pieterse 1978). Their non-occurrence at Arnot may indicate the existence of a marked climatic gradient between the palaeolatitudes of Arnot and the south-western Cape or it may simply indicate the existence of a montane habitat in the latter region. It is clear, however, from evidence from elsewhere (Herngreen & Chlonova 1981: 506, 511) that Microcachryidites is a sensitive indicator of some climatic gradient.

Microcachryidites is still a prominent component of the Neogene vegetation of the south-western Cape, while Araucariacites does not appear in the Neogene record (Coetzee 1978a, 1978b, and pers. comm.). No species of Microcachrys occur today in Africa.

It would appear that one Zonalapollenites form as well as Podocarpidites riembreekensis and perhaps Podocarpidites kamiesbergensis are at present unique to the southern African Palaeocene.

(c) The absence of a number of angiospermous forms characteristic of the Australian Palaeocene from the Arnot assemblages provides further contrasts. These include the three Nothofagus pollen types (although these are only common from the Eocene in Australia), Myrtaceae, Olacaceae (Anacalosa), Euphorbiaceae (Austrobuxus—Dissiliaria), Banksieae, Xylomelum-type and other extinct forms attributed to the Proteaceae, Santalaceae, /lex (Aquifoli- aceae) and Cupanieae (Sapindaceae).

On the other hand the following forms that occur at Arnot are not known from the Australian Palaeocene: Triorites operculatus and T. sphericus (the former very prominent), Retistephanocolpites (prominent earlier (?) in the Palaeocene from other sites in Namaqualand), Crototricolpites and Crotonipollis (Euphorbiaceae), Grootipollis (Thymelaeaceae), all the proteaceous forms (3-4?), Milfordia (Restionaceae), Rhus (Anacardiaceae), Triporotetradites, two monocolpate forms (one, and perhaps both, of which have affinity to the Palmae), a palmaceous Liliacidites, Tricolporopollenites arnotiensis and T. brinkiae (Rubiaceae, Euphorbiaceae?), and Tricolporopollenites spp. C & D (Cornaceae).

9. Apart from the absence in the tropical African late Cretaceous—early Tertiary record of the spore and conifer ‘temperate’ southern Gondwana floral component, the most important contrast between the Arnot and tropical palaeofioras lies in the representation of palms. In the Palaeocene of tropical Africa, twelve palm form-genera are recognized and their representation is constantly high (20-25%) (Salard-Cheboldaeff 1981). At Arnot two to three forms with affinity to the Palmae occur and their contribution to the palynomorph assemblages never rises above 3 per cent.

94 ANNALS OF THE SOUTH AFRICAN MUSEUM

As already indicated very few form-genera occur both at Arnot and in Palaeocene tropical African palynomorph assemblages (12 %), while the relation- ship is closer at a high taxonomic level, with 65 per cent of the families being common to both.

The forms common to both regions are Foveotriletes margaritae, Distaverru- sporis, Zonalapollenites sp. B (Cingulatipollenites), Monocolpopollenites sp. B, Celtidoideae? (Triorites operculatus—Triorites festatus/tenuiexinus), Crototricol- pites, Ulmipollenites sp., Proteaceae (Propylipollis meyeri—Proteacidites de- haanii).

The families Olacaceae, Ctenolophonaceae, Malphigiaceae, Moraceae, Acanthaceae, Mimosaceae, Bombaceae, Apocynaceae, Balanophoraceae, Mela- stomaceae, and Combretaceae are recorded in tropical African assemblages (with some genera being prominent) but are not known from Arnot.

A less biased reflection of differences between the tropical African and - Arnot Palaeocene floras is provided by the list of families that, as far as is known, occur only in the latter region: Anthocerotaceae, Sphagnaceae, Podocarpaceae, Araucariaceae, Chloranthaceae, Myricaceae, Ericaceae, Epacridaceae, Gunner- aceae and Cornaceae.

10. These comparisons introduce an attempt to reconstruct the palaeo- vegetation and climate of the Arnot region. Two informal methods are used to achieve this end. The first (points 15-18 below) involves bracketing the Arnot climate between what has been suggested were the conditions pertaining to palaeolatitudes to the north, south, and perhaps east of it. The second (points 18-19 below) involves extrapolating from knowledge of the present-day distribution, habitat requirements and common growth forms of a set of taxa, to form a hopefully coherent picture of the palaeovegetation. Table 2 provides a list of the families and genera thought to be represented in the Arnot palynoflora, together with notes on their present distribution, habitat and common growth form.

11. The limitations of the second method are well known. It is clear, merely from the presence of both Araucariacites and the Dacrydium cupressinum pollen type at Arnot (compare the present-day habitat requirements of the genera given in Table 2), that a process of differentiation of climates and vegetation has probably occurred between the Palaeocene and today. Taxa such as Araucaria and Dacrydium must have evolved relatively narrower habitat tolerances through time, i.e. are confined to those habitats most suited to their evolutionary potential, as a response to the development of a greater range and distinctiveness of climates through time (cf. Kemp 1981: 40). The suggestion is therefore that both the vegetation and climate recorded at Arnot were part of more uniform, equable and extensive distributions of climate and vegetation (see point 13 below).

In this connection it is relevant to note that Truswell & Harris (1982: 71) in their review of the palynology of the Eocene of Australia also mention the occurrence of palynological assemblages containing a mixture of elements, which

PALYNOLOGY OF THE ARNOT PIPE 95

are not found growing together today, e.g. tropical rain forest and temperate rain forest taxa.

12. Along with this observation goes the realization that it is only in a qualified sense that concepts such as ‘tropical’ or ‘warm temperate’ can, by extrapolation from the present, be used to describe the Palaeocene vegetation or climates. This is not only because Palaeocene climates may have been very different from modern climates, but also because these concepts are not basic enough categories with which to understand even modern-day vegetation of climatic types and distributions. Webb & Tracy (1981), for instance, use twenty- one categories to describe the range of Australian rain-forest structural types and nine categories to link these structural types to climatic and edaphic factors. They argue that the recognition of the structural types enable better phytogeographical and historical biogeographical analyses to be made between Australian and extra-Australian regions, a claim that suggests that they have developed basic categories with which to understand their phenomena.

13. At a general level, the mechanics of global air circulation systems are relatively simple and therefore amenable to extrapolation to the past. Using these mechanics and assuming the equator—pole temperature gradient of a polar- ice-cap-free world, Lamb (1972) has modelled pre-Oligocene atmospheric circulation. Between the equator and 60° latitude the development of pressure anomalies would have been counteracted, not by prevailing lower and upper atmosphere winds as is the case today, but by moving cells of higher and lower pressures, cooler and warmer air. A weak and erratic Ferrel-type circulation would have resulted. This type of circulation, involving the lack of zonal wind systems, is essentially unknown today and an implication of this model is that there are no close present-day analogues for pre-Oligocene climates and vegetation.

This is not to suggest that, in terms of this model, some climatic gradient between 0 and 60° latitude did not exist. An insolation gradient alone must presumably have existed, but Lamb’s model suggests that pre-Oligocene climates in low and middle latitudes were more uniform, perhaps more equable, extensive and mildly transitional than is the case today. The climate of a particular region would still have been determined by its latitude and location in terms of the configuration of warmer and cooler seas and continents, mountains and lowlands, and its continentality.

However, Parrish & Curtis (1982) and Parrish et al. (1982) do not accept Lamb’s model for pre-Oligocene climates and, using an analysis of the distribution of upwelling and organic-rich rocks and evaporites, have determined atmospheric circulation and precipitation patterns. From this they have produced a series of global maps portraying the broad relative isohyets of precipitation predicted by their climatic model for various stages in the past. For the time range concerned Parrish et al. (1982: 80) suggest that the Arnot region would have received a relatively low to moderately low rainfall.

96 ANNALS OF THE SOUTH AFRICAN MUSEUM

Visualizing the Arnot palaeovegetation and climate in relation to those to the north and south should be done with Lamb’s (1972) model and the predictions of Parrish et al. (1982) in mind. It is at present not clear how real the contradictions between the two models involved are. Kemp (1978, 1981) has used Lamb’s model to reconstruct early Tertiary Australian climates and vegetation.

14. Both the predictions of Parrish et al. (1982) and the features of atmospheric circulation described by Lamb (1972) allow one to maintain (contra Axelrod & Raven 1978) that there is no immediate climatological reason why, during the time range concerned, a zone of sharply transitional climate should have been located in the general Arnot region producing an ecotonal state of vegetation. Also, as stated in a previous section, there is no reason to assume that high relief existed in the Arnot region. For these reasons, and until evidence to the contrary exists, one should attempt to reconstruct the Palaeocene Arnot

vegetation as a single unit.

15. The comparisons made between the Arnot and tropical African palynofloras (points 6 and 9 above) highlighted the paucity of common elements. The Arnot palaeoflora was clearly not part of a Palaeocene African ‘tropical’ flora.

However, it should be noted that Salard-Cheboldaeff (1981) has suggested that the climate of Africa in low latitudes during the Maastrichtian was warm, temperate and dry and that the drastic floral change recorded at the Cretaceous— Tertiary boundary could be explained by a cooling episode in the early Palaeocene. Many palynological studies have documented floral change at the Cretaceous—Tertiary boundary (Muller 1980) and a Palaeocene cooling is generally accepted to have occurred world-wide. There is disagreement, however, as to the scale of change attributable to this factor and its relationship to the complex global environmental changes that took place at this time (Muller 1980). Further evidence relevant to low-latitude climates in the Palaeocene comes from Muller’s (1980) reconstruction of the latitudinal ranges of various thermophilous taxa through the Palaeogene. This reconstruction suggests that their ranges were most constricted in the Palaeocene, i.e. that during the Palaeogene temperatures were lowest in the Palaeocene itself.

16. The exiting of Araucariacites from the tropical African record during the late Cretaceous and at the Cretaceous—Tertiary boundary in India, and its continued occurrence in the Arnot region and in Australia in the Palaeocene, can obviously not be explained only in terms of cooler episodes in the Cretaceous and Palaeocene (Australia and the Arnot region at mid-latitudes would at least have had cooler winters than the equatorial regions), but must also be related to increased precipitation or the development of more equable climates in the tropics. The suggestion is, therefore, that in addition to a climate cooler than that of the tropics, a climate drier or less equable than that experienced in the Palaeocene ‘tropical zone’ is indicated by the occurrence of Avraucariacites at Arnot.

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PALYNOLOGY OF THE ARNOT PIPE 97

However, there is a possibility that factors other than climatic change could affect the abundance of conifers relative to angiosperms in a vegetation. Doyle et al. (1982) have recently reviewed hypotheses explaining the prominence of gymnosperms (Cheirolepidaceae, Araucariaceae, and Podocarpaceae) in the mid-Cretaceous tropical floras, their subsequent decline in the late Cretaceous, and the concomitant rise to dominance of the angiosperms. Apart from the limited evolutionary potential of conifers in the tropics, imposed by their lack of vessels and stereotyped leaf morphology and photosynthetic ability, the use made by their competitors—the angiosperms— of insect pollination, to produce highly dispersed populations and high species diversity may have contributed to their demise. “With continued diversification, the ability of angiosperms to pack more species into a given area might have eventually led to the collapse of gymnosperm communities by competition from many sides and dilution of populations below a level of effective wind pollination’ (P. J. Regal, pers. comm. in Doyle et al. 1982: 86). It should be noted that, to judge from pollen morphology, a large component of the Arnot angiosperm palaeoflora was anemophilous, perhaps leaving the coniferous component in a better position to maintain minimum population densities (see point 21 below).

17. The comparisons made between the Arnot palynoflora and the south- eastern Australian record (points 6 and 8 above) suggest that the Arnot palaeoclimate was neither as cool nor as humid or equable as the ‘temperate’ climate indicated (especially by the composition and representation of the conifer and spore flora) for south-eastern Australia. The odd occurrence of putative ‘tropical’ indicators such as Anacalosidites or Cupanieidites in the Australian early Tertiary (Wopfner et al. 1974: 47) may be recording the tolerance of these taxa to low levels of insolation in combination with high equability of climate (the effect of eastern location of sites, a warm palaeo-Pacific Ocean, and low relief?) rather than high ‘tropical’ temperatures.

18. As might have been predicted, therefore, the comparative sandwiching of the Arnot palaeoclimate indicates that it was a warm, moderately equable and, relative to the ‘tropical’ norm, dryish type. Climates of this general type are found in subtropical and warm temperate regions today. The fact that the present-day distributions of most of the taxa listed in Table 2 are within the tropics and subtropics therefore lends some support to the above climatic reconstruction.

The best modern analogy for the vegetation that could have grown under such a climate might be some of the drier forest types of east Africa, or perhaps the mixed araucarian notophyll or microphyll vine forests of north-eastern Australia. These are described by Webb & Tracey (1981: 626, fig. 4) as moist forest types growing under a mean annual rainfall of 700-1 200 mm.

19. An inspection of the information on growth forms in Table 2 suggests that the vegetation in the Arnot region was forest. Trees are the most common growth form and lianes, epiphytes, tree-ferns, forest-floor mosses and forest- margin species are possibly also represented.

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ANNALS OF THE SOUTH AFRICAN MUSEUM

TABLE 2

Families and genera that, it is suggested, occur at Arnot, with notes on their present distribution, size and common growth forms. (Information mainly from Willis 1966.)

Taxon

Alangiaceae (?)

(2 genera, 20 species)

Anacaridaceae

(60 genera, 600 species) Rhus (250 species)

Anthocerotaceae

_Araucariaceae

(2 genera, 38 species)

Cactaceae (?)

(50 genera, 2 000 species)

Caesalpinaceae

Bauhinia (?) (30 species)

Casuarinaceae

(2 genera, 65 species) Casuarina (?) (45 species)

Cornaceae

(12 genera, 100 species)

Cornus

Cyatheaceae

Epacridaceae (?)

(30 genera, 400 species)

Ericaceae

(50 genera, 1 530 species)

Euphorbiaceae

Adenocline (18 species)

or Klaineanthus (1 species) Zimmermania (?) (4 species) Croton (?) (750 species)

Notes

Tropics. Trees and shrubs.

Chiefly tropical, but also warm temperate areas. Trees and shrubs.

Widespread in tropical and subtropical regions. Much- branched shrubs, or, more rarely, trees.

Mosses mainly with a circumboreal distribution, but also in the Mediterranean region. Hygrophytic on slightly wet sandy soils rich in loam and mostly near forests (Boros & Jarai-Komldédi 1975).

Southern Hemisphere, except Africa. Trees. Moist sub- tropical and tropical non-monsoonal forests. In Argentina Araucaria araucana is dominant in the forest of the Subantarctic floral province.

Xerophilous growth forms of the most pronounced type. Chiefly in the drier regions of tropical America, but also reaching British Columbia and Patagonia. In forest regions there are several epiphytic genera. One genus, Rhipsalis, in Africa.

Warm regions. Mostly lianas; also trees and shrubs.

Trees or shrubs, often of weeping habit.

East Africa (? native), Mascarene Islands, Australasia.

Northern and Southern hemispheres; temperate regions and on mountains in the tropics. Trees and shrubs, rarely herbs.

Trees. Europe, east Asia and North America.

Tree-ferns on all southern continents.

Indo-China to New Zealand, Hawaii, South America but chiefly Australia and Tasmania. Representing the Ericaceae of other continents. On heaths and boggy ground. Mostly like Ericaceae in habit, usually shrubs or small trees.

Confined to Africa, Mediterranean and Europe in two main masses separated by the Sahara. Cosmopolitan, usually confined to high altitudes in the tropics; also on moors, swamps, and peaty soils. Woody; small undershrubs to large shrubs and a few small trees.

One of the largest plant families. Cosmopolitan in tropical, subtropical, and warm temperate regions. Trees in the tropics; also herbs and shrubs.

Southern Africa. Herbs.

Tropical west Africa. Giant forest trees.

Tropical east Africa. Trees.

Tropics and subtropics. Trees.

PALYNOLOGY OF THE ARNOT PIPE 99

Taxon

Gunneraceae (1 genus, 50 species)

Lophosoriaceae (2 genera, 2 species)

Monimiaceae (20 genera, 150 species)

Ophioglossaceae (4 genera, 70 species)

Palmae (217 genera, 2 500 species)

Chamaedorea (?) (100 species)

Podocarpaceae (6 genera, 125 species)

Dacrydium (25 species)

Polypodiaceae (50 genera)

Proteaceae (62 genera, 1 050 species)

Restionaceae (28 genera, 320 species)

Rubiaceae (500 genera, 6 000 species) Anthospermum (?) (50 species)

Schizaeaceae Schizaea (30 species)

Sphagnaceae (1 genus, many species)

Thymelaeaceae (50 genera, 500 species)

Notes

In the tropics and southern temperate regions. Perennial thizomous herbs. Widespread in southern Africa, except South West Africa—Namibia.

Small tree-ferns of tropical South America.

Chiefly southern tropical and especially in the ‘oceanic’ floral regions. Shrubs and trees with leathery ever- green leaves.

Tropical and temperate regions. Small herbs, and some tropical species are epiphytic.

Tropical and subtropical. Some are widespread, but most genera are well localized. The palms form a charac- teristic feature of tropical vegetation. Trees.

Warm America. Small reedy palms often forming suckers.

Southern conifers. Present on all southern land-masses. Wide range of habitats; lowland heaths and scrubs, open forest, rain-forest and subalpine vegetation. Trees or shrubs.

Indo-Malaysia, Tasmania, New Zealand. Trees and shrubs. Temperate rain-forest. Cool wet sclerophyll forest. Mainly found in cool temperate Tasmania. ‘Frees:

Cosmopolitan, especially in the wet tropics. Almost all are epiphytes.

Tropical Asia, Australasia, South America; tropics and temperate areas, also mountains in Africa, South Africa and Madagascar. The great majority live in regions where there is annually a long dry season. The primitive members of this family are mostly rain-forest trees.

Mostly in southern Africa and Australia; a few in New Zealand, Chile, Indo-China and tropical Africa. Xerophilous, perennial with a tufted or creeping rootstock.

One of the largest plant families. Most are tropical but a number are temperate. Trees, shrubs and herbs. Africa and Madagascar. Widespread, associated with afromontane vegetation. Low shrubs and herbs.

Mainly in the tropics, but also North America. All southern continents.

Peat-moss family. Forms peat bogs and is common on wet forest floors and shaded mountain seeps.

Temperate and tropical regions, especially in Africa. Most are shrubs, but there are some trees and a few lianas and herbs.

100 ANNALS OF THE SOUTH AFRICAN MUSEUM

Taxon Notes

Ulmaceae (?) Cosmopolitan. Mainly in the Northern Hemisphere tem- (15 genera, 200 species) perate regions and tropics. Celtis (?) (80 species) Cosmopolitan in tropics and temperate areas. Very

widespread in southern Africa, except South West Africa—Namibia. Trees with a range of adaptability and growth form.

Ulmus (?) (45 species) (Elm.) North and south temperate regions. Trees.

20. Can any suggestion be made as to the habitat of members of the Ericaceae, Epacridaceae, Restionaceae and Proteaceae, and perhaps also Rubiaceae and Thymelaeaceae, which may not have been, or were not, trees within the suggested general forest environment? What implications does this

have for ideas about the origins and evolution of the Cape fynbos? . No very positive statements can be made, but there are some suggestions that these taxa could have been part of the understorey of a dryish open forest type. The implication is that the origin and evolution of the fynbos is linked, in its earlier stages, to the history of this vegetation type rather than to the history of cooler, wetter, perhaps more closed-canopy forest types, such as may have been present to the south of Arnot, or in montane situations (Coetzee et al. 1983).

The following observations provide the basis for these statements:

(a) The counter-suggestion that the distribution of these taxa may have been controlled by the occurrence of specific edaphic conditions receives little support from the available evidence. There is no floristic indication of the existence of swampy or water-logged conditions in the vicinity of the site and the suggested local topography (p. 5) argues the same. Also, the local substrates and sediments of the pipe itself indicate that no oligotrophic soils occurred in the vicinity of the pipe. Therefore, Specht’s (1979, 1981) hypothesis as to the possible origin of sclerophyllous taxa cannot, in this instance, be supported. In terms of his hypothesis, under a warm, humid, equable climate local edaphic sites such as water-logged areas, or areas of oligotrophic soils, could have been the areas where early sclerophyll communities originated.

(b) Ericaceae are not recorded in the Knysna lignites (Thiergart et al. 1963), which may be either Eocene—Oligocene or early Miocene in age, and are very rare in the early Miocene lower levels of the Noordhoek occurrence (Coetzee 1978a, 1978b). There is evidence to suggest that the vegetation types represented at these sites were adapted to relatively wetter and more montane and equable climates than the Arnot palaeovegetation. Restionaceae are also either very rare or absent from the lower levels at Noordhoek, but are the most abundant type in the Knysna lignites. These latter restionaceous forms, however, are different to the Arnot (Milfordia) forms, having graminoid-type apertures, and their abundance has been taken to indicate extensive marshlands in the vicinity (Thiergart et al. 1963).

PALYNOLOGY OF THE ARNOT PIPE 101

(c) Evidence from Arnot and Botswana (Scholtz & Deacon 1982; Coetzee et al. 1983) suggests that some zonation of forest vegetation existed during the late Cretaceous and early Tertiary in the subcontinent, and that forms with affinity to Restionaceae, Ericaceae and Proteaceae did occur in the probably relatively drier north-western interior.

(d) Monulcipollenites confossus, a restionaceous form, exits from the tropical African record at the Cretaceous—Tertiary boundary (Salard-Cheboldaeff 1979). This pattern may relate to the development of wetter and more equable climates and closed-canopy forest during the Palaeocene. In this connection Whitmore (1975, quoted in Webb & Tracey 1981: 613) has attributed the poverty of the south-east Asian rain-forest grass flora to the relative stability of these humid, closed-canopy forests. In more open and disturbable forest types (i.e. under drier and less equable climates) the evolution of nomad grass species is favoured.

The generalized point is of importance in this discussion. Drier, less equable, open-canopied forest types are the forest types within which an understorey will evolve. The origins and evolution of the fynbos may therefore be linked to the history of drier forest vegetation. In this view the fynbos shares an origin with other generally ‘subtropical’ vegetation associations from which it has been separated by the subsequent development of more diverse climates.

If this hypothesis is correct and it can be more adequately demonstrated that in the early Tertiary members of the Proteaceae, Ericaceae and Restionaceae were widespread in non-montane vegetation, then their supposedly typical present-day distribution in Africa, high diversity in, and dominance of, the montane vegetation of the south-western Cape, and association with nutrient- poor soils are all ‘secondary’ features. The present pattern of their distribution should then be viewed as being achieved as climates diversified and became, in general (excepting especially mountains that receive orographic rain), more arid through time. In this process earlier dominant types of vegetation and taxa were presumably eliminated and in situ evolution of other components of vegetation resulted in new vegetation associations, specialist adaptions, etc.

(e) The above evidence and argument suggest that Johnson & Briggs’s (1981: 463) attempt to outline the history of scleromorphic flora may need qualification. Central to their hypotheses was the idea that, following Specht (1979, 1981), the scleromorphic flora originated by the early Palaeogene in the adaption to patches of oligotrophic soils within forest vegetation. Secondly, they suggest that this scleromorphic flora has a history as a unit through into its present prominence in areas of Mediterranean climate and poor soils.

The evidence from southern Africa suggests otherwise. In the first place, it appears that during the early Tertiary in the Arnot region members of the Ericaceae, Restionaceae, Proteaceae and Thymelaeaceae (and perhaps Rubi- aceae) grew on eutrophic soils within a lowland, probably extensive, forest, growing under a warm dryish climate. Although local edaphic factors such as forest disturbance (fire?), steep slopes or thin soil cover may have favoured their

102 ANNALS OF THE SOUTH AFRICAN MUSEUM

growth, they must basically have been widespread within the forest, i.e. part of the understorey. Secondly, this evidence taken together with (i) the dominance of Restionaceae with graminoid apertures (unlike those recorded at Arnot and like most extant southern African Restionaceae), (ii) the absence of Ericaceae in the Knysna lignites (Thiergart et al. 1963) and (iii) the paucity of Restionaceae, Ericaceae and Thymelaeaceae at Noordhoek (a site rimmed by mountains of Table Mountain Sandstone, and therefore with very oligotrophic soils) in the south-western Cape in the early Neogene (Coetzee 1978a, 1978b), suggests that the origins of the present scleromorphic Capensis Flora are polyphyletic and that the evolution of its components and history of its synthesis is complex.

Lastly, as suggested by Axelrod & Raven (1978) and Parrish et al. (1982), relatively xeric vegetation may have a long history in the African subcontinent. If this were so, comparative studies might show that relatively more of the older scleromorphic taxa in the region were in fact truly sclerophyllous than is the case, - for instance, in Australia.

21. The contribution of the Arnot evidence towards a preliminary outline of the vegetation history of the African subcontinent during the late Cretaceous and early Tertiary is discussed elsewhere (Coetzee et al. 1983). It suffices here to say that at present the Arnot palynoflora records the first modern angiosperm flora known in the African subcontinent after the extinction of the late Cretaceous, archaic angiosperm flora in which Ephedripites, Fenestriorites, Cretacaeiporites, Hexaporotricolpites and Proteacidites forms are prominent (Scholtz & Deacon 1982). The strong representation of forms such as Triorites operculatus, T. sphericus and T. harrissii may relate to the often-recorded increase of triporate forms with affinity to families such as the Betulaceae, Ulmaceae, Carpinaceae or Casuarinaceae in the Palaeocene (Chourey 1974; Srivastava 1981). This phe- nomenon has been taken, in conjunction with other evidence, to indicate a cooling event in the early Palaeocene. Also, it has been suggested by Whitehead (1971), amongst others, that the appearance of relatively small, triporate, psilate angiosperm pollen indicating secondary adaptation to anemophily, coincides with the appearance of the deciduous habit and seasonality of precipitation.

22. Lastly, the floral changes recorded within the Arnot sequence, as well as the very different palynomorph assemblages known from the region and from ‘kimberlite’ pipe sequences from Botswana, raises a general point about the possible differences that will be encountered in the study of vegetation change based on ‘kimberlite’ pipe sequences, versus studies based on the more usual depositional site sequences.

As already suggested, the crater lakes of ‘kimberlite’ volcanoes formed small sedimentary traps positively unrelated to developed drainage patterns. It can be assumed that their palynomorph assemblages were the result of wind and very local water transport. In addition, the rate of their infilling is likely to have been rapid. They will, therefore, reflect vegetation change to much finer scale than is the case with larger epicontinental or deep-ocean sedimentary basins. This poses

PALYNOLOGY OF THE ARNOT PIPE 103

some problems for palynological work but, because of the abundance and distribution of these sites, creates the potential for a detailed understanding of vegetation associations, distribution and history in the time ranges concerned.

ACKNOWLEDGEMENTS

This research was funded as a project within a Council for Scientific and Industrial Research—Cooperative Scientific Programmes (CSIR-—CSP) project, the Fynbos Biome Project (Palaeoecology of the Fynbos Biome Subproject). The research was originally started as part of input into the review paper “The comparative evolution of Mediterranean-type ecosystems’ prepared by Professor H. J. Deacon of the Department of Archaeology, University of Stellenbosch for the CSIR-—CSP-funded conference on Mediterranean ecosystems (MEDCON 1980). The help and advice of Professor H. J. Deacon is gratefully acknowledged.

Mrs C. E. Stevens of the Department of Archaeology, University of Stellenbosch, gracefully typed and retyped the manuscript, and painstaking care was taken in producing the photomicrograph prints by Elsabé Pretorius. Many thanks also to Mr A. P. and Mrs Christine Meyer, and to Esmien and Jannie Louw of the farms Banke and Riembreek respectively, for their friendship and hospitality.

Helpful criticism of the manuscript was received from Professor E. J. Moll, Dr L. Scott and Dr E. M. Truswell (formerly Kemp). Dr M. Cluver of the South African Museum kindly made the samples available for study. I am very grateful to Miss E. Louw for considerable editorial assistance.

The University of Stellenbosch provided a generous grant towards part of the publication costs of this work.

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