Rostrumaspern~umvenkatachalae gen. et sp. nov., an archegoniate seed from of Nidpur, India

Shvam C Srivastava & S. R. Manik

Sril·aSlal·a. Sl1yam C. &. 1\lanik. S. 1<. 1'.>90. !

Some carbonized seeds recolered from plal1l·bearing Nidpur beds are assigned to ROSlrllmaSp"rl1ll1l1l l'I!/lkCIIl/cb(/lul! gen. et sp. nOI h'idence llf arehegollia lI'itl1 shon lLlbular neck favours idcntir)' with conifers and

~elilesprecisel\' pineaceous affi! i;1lions.

Key-words-l\-legafossil, Archegoniate seed. 1\lorpl1,llogy, Triassic (India)

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CONTINUED investigations of -bearing Nidpur 1919) described a definite megaspore membrane beds have yielded a number of carbonized seeds. surrounding prothallus tissue bearing two One of these structurally preserved seeds which is archegonia. Later, Seward (19]9) dealt in detail the characterized by the occurrence of tubular structural features of Cardiocarpus sclerotesta archegonia at the microp>lar end of megaspore sac Brongnian and showed a well·developed pollen has constituted the matter for this paper. Of the .::hamber. Below the chamber, the prothallus tissue is reponed seed taxa (Pant, 1978; Manik, 1988) from prolonged as a blunt, shon tentpole along which on Nidpur, namely Rugaspermum, Savitrispermum, each side two small archegonia are located. He also Nidispermum, Pyrijormispermum, Rotundaspermum instituted a seed taxon Rhabdospermum cyclocarpon and Pantiaspermum, none has revealed any such and reponed the presence of single archegonium feature. However, among the various fossil through illustrations of megaspore sac (Seward, gymnosperms, only a few members of 1919, fig 501-C, p. 340) Long (1944) observed three Glossopteridales, Pteridospermales, Bennettitales archegonia towards the apical end of female (= Cycadeoidales) and Cordaitales have shown gametophyte around the tentpole in a Palaeozoic archegonia at the apical end of megaspore sac. To pteridospermous seed-Lagenostoma ovoides add, all living members of gymnosperms are also Williamson 1877 Long (1959, 1960) opined that characterized by the presence of archegonia with an Lower seeds are the first known to exception' of Welwitschia and Gnetum (Maheshwari contain archegonia, with three archegonia being the & Sanwal. 1963) most common number. Taylor and Millay (1979) Renault (1879) figured archegonia in marked a well-developed archegonial cavity in L. Cycadinocarpus angustodunensis from of ovoides. France. Since then, Brongniart (1981. in: Seward, Since the discovery by Long was highlighted, 98 SRIVASTAVA & ~'lANIK-ANARCHEGONIATE SEED FROJvl THlASSlC 99

In addition, Rothwell (1971) reported ovoid cavities at the micropylar end of the megaspore sac of Callospermarion pusillum Eggert and Delevoryas 1960 and interpreted them to be archegonial cavities, However, in Callospermarion undulatum, described by Rothwell (1981), the definitive archegonia could be marked with tubular necks, But distinct number of archegonia could not be marked, In this character of tubular neck, C undulatum approaches closest to the seed described here, Aparr from this, Stidd and Cosentino (1976) were able to make out neck canal cells in the sunken archegonia of Carboniferous ovule Nucellangium Andrews 1949, Other than these Palaeozoic seeds from northern hemisphere, interesting records of archegonia have also been made by Pant et at. ( 1985) from the Permian sediments of India, The twO seed-genera described are: Collospermum and Palaeocarpus in which megaspore membrane is raised and prolonged into a tentpole-like structure, Under the surrounding depression, two or three spherical dark bodies are seen which are presumed to be archegonia on the basis of the presence of similar spherical archegonia found in cordaitalean and ginkgoalean seeds, From Late Permian of Bowen Basin, Queensland, Australia, Gould and Delevoryas (1977) have reported glossopteridean megasporophyll bearing seeds containing megagametophyte with one archegonium, The aforesaid records have demonstrated varied archegonia in petri factions and compressions of Palaeozoic seeds, but from Mesozoic not much is known, The first record came to light when Lignier (1911) in a reconstruction of Cycadeoidea Text-figure l-Roslrllmaspermlll7l uenkalacbatae gen. et sp. (Bennettites) morien' (Lower of France) nov., reconstruction of seed depicting overall shape, various illustrated the presence of archegonia in the apical curinized membranes associated with archegonia; in miLkUl· open to show a pan of megaspore sac Ca x 50. part of endosperm, However, Seward (1919) raised doubt regarding the occurrence of archegonia Neely (1951) described Taxospermum undulatum because the seed of C morien' contains a well and depicted the megagametophyte with one developed embryo, Since then, the occurrence of spherical or elliptical archegonium on either side of archegonia remained unknown till Sharma (1979), the low tentpole. In this Pennsylvanian seed, Taylor observed 2-3 archegonia in the apical parr of and Millay (1979) identified a megagametophyte endosperm of Williamsonia-ovules described from which is well-differentiated into a tentpole and the Mesozoic of Rajmahal Hills, Bihar. archegonium containing cytoplasmic remnant, The gametophyte of Pachytesta hexangulata Stewart 1951 Rostrllmaspermllm gen. nov. consisted of shoft tentpole with three archegonia Diagnosis-Seed ovate, tapering apically around it. Andrews and Felix (1952) reported somewhat like a snout, micropylar end appearing tentpole and a two jacketed archegonia in the female flattened, integument in outer region thin on flanks gametophytes of Cardiocarpus spinatus Graham and base, tending to be highly developed at apex, 1935, Andrews (1961, fig, 13-3B) figured a Lower forming an outer integument characterized in Carboniferous seed, Sphaerostoma ovale Benson extremities by radially disposed spaces; cellular 1914, where archegonia can be clearly marked but structure of integument contorted revealing surface the author has made no mention of it in the wall interspersed with pits, outer integument closely description, abutted to nucellus; nucellar membrane thin, ]00 THE PALAE0I30TANIST

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Text-figure 2-NoSlr/ll1laSpprlll/l1ll I'ellkatachalae gen. et sp. no\·., A. Seed (alkali treated) showing o\erall Olltline and chalazal end, Slide no. BSIP 10272. x 2~;B. A portion of megaspore sac adhered at places with nucellar membrane. Slide no I3SIP 10270. x 2~0; C. A pan of microp\'lar end sho\Ying radially disposed spaces interspersed with irregular pits. Slide no. HSIP 10270, x 2~0;D. Apical region of seed eXhibiting imensivel)' cutillized flanened micropylar end. Slide no. BS1P 10271. x ] ~o;E. A piece or aliter integument sho\ving cellular details. Slide no 13S[1'102 7 0, x 2~0;F. Apical region or megaspore sac showing t\',,"odistinct archegonia, Slide no BSIP 10270, x I ~O.

--+ PLATE 1

RostrlllJlaspermUII1 I'enkatacbalal' gen. e( sp. no\'. spersed with irregular pits, Slide no BSIP 10270, x [50 1,7 Carbonized seeds immersed in glycerine showing overall 5. Apical end of seed magnified to show two spherical arche­ outline. micropylar and chalazal end (Holorype); Slide nos. gonia and distinctly differentiated radially disposed spaces. BS1P,10270, x 10; J027I, x 10. Slide no 13SIP 10270, x ~o 2. Acid-treated seed depicting differentiation of cutinized 6 Megaspore sac highly magnified to show t\VO distinct arche­ membranes, specimen no BS1P 10270, x 50. gonia having tubular neck, Slide no. BSIP 10270, x 300. 3. Macerated seed after complete processing showing mega­ 8. Seed shmving flattened lOp of micropylar end, Slide no. spore sac bearing (wO archegonia occupying almost entire BSIP 10271, x 50 space of nucellus, Slide no_ BSIP 10270, x 25 9 Terminal portion of seed exhibiting distinctly differentiated 4. A portion of seed showing radially disposed spaces imer- nucellar depression. Slide no. BSIP 10272. x 50. o

~ z o v 102 THE PALAEOBOTANIST

confluent to megaspore membrane, free from outer breadth; chalazal end broadly rounded, tapering integument at its apex; megaspore membrane towards micropylar end having flattened apex; bearing two archegonia, occupying almost entire somewhat looking like apical snout; integument space of nucellus, forming ovoid to ovate sac. consisting of outer region tending to be thin along Type species- Rostrumaspenn u m uenkatachalae flanks and base, highly developed at apex, forming sp. nov. outer integument characterized by radially disposed Discussion-In its overall shape the present spaces; structurally outer integument composed of seed taxon differs from all the known seed genera irregular cells with their surfaces interspersed with described from Nidpur plant beds in bearing pits of varying sizes, pits frequently occurring in characteristic apical snout. Further, it stands apart hemispherical disposed spaces, entire from Rostrumaspermum because of lack of integumentary cellular organization appearing to be archegonia in their megaspore sac. In the striking contorted, integument closely abutted to nucellus features of archegonia, Rostrumaspermum compares but free at apex; nucellar membrane confluent to with detached petrified seeds mostly known from megaspore membrane, composed of thin-walled, Palaeozoic sediments of northern hemisphere but elongated, rectangular-polygonal cells distinctly the present taxon being compressed, obviously seed marked over the megaspore body; micropylar lacks vascular supply and the other anatomical opening ± rounded, intensively cutinized depicting details and thus it can be easily differentiated from radially elongated cells; megaspore obscured in all such seeds. The twO taxa preserved as cellular details, dark-brown in colour occupying petrifactions, viz., AetbeotestCt elliptica Renault 1896, maximum space of nucellus, more or less forming an and Rhabdospermum tunicatum Seward 1919, ovoid to ovate sac; at the micropylar end of possessing radially disposed spaces and apical megaspore sac two dark spherical bodies bearing snout, have exhibited close identity with the genus tube-like neck considered as to be archegonium Rostrumaspermum but in other characters, because present; archegonia highly cutinized, cell outlines of being in petrified state, these genera readily differ not discernible; between the two archegonia a from R. uenkatacbalae. cutinized mass superposed by one of the archegonia The other petrified taxa, viz., Lagenostoma somewhat rounded flattened in structure distinctly ouoides, Pacbytesta bexangulata, CycadinocaJpus marked and interpreted as to be immature angustodunensis, Cardiocarpus spinatus, archegonium. Taxospermum undulatum, markedly differ from R. Holotype-Slide no. BSIP 10270. uenkatachalae in having two archegonia flanking a Locality-Nidpur, Sidhi District, Madhya "tentpole" at the distal end. Pradesh. The new genus also compares with the seed Age-Middle Triassic. compressions: Collospermum and Palaeocarpus Remarks-Nucellar cuticle is mostly fused with reponed from Lower Gondwana (Karharbari the megaspore membrane and occasionally cellular Formation) of India (Pant et al., 1985) in the markings or imprints are seen over megaspore body. presence of archegonia but R. uenkatachalae At times, because of over maceration, seed-cuticles distinguishes itself from the latter two genera in its split into pieces and the two layers of megaspore sac tubular archegonia and distinctive apical snout. Also, become evident which is indicative of double nature the new genus lacks well-differentiated tentpo!e as of megaspore membrane. Other seed specimens has been exhibited in the aforesaid Permian seed­ belonging to R. uenkatachalae have not shown the compressions. presence of archegonia but the pits have been Further, the occurrence of tubular archegonia in commonly observed in the radially disposed spaces. R. uenkatachalae suggests that this seed might Absence of archegonia may be due to the fact that belong to which could be allied to Cordaitales the development of archegonia might have been or Ginkgoales. However, this possibility is remote deferred until female gametophyte is completely because no fructifications referable to these groups cellular (Foster & Gifford, 1974). have so far been recorded. Besides, in possessing Comparison-In characteristic features of snout­ short tubular archegonia R. venkatachalae is like structure and occurrence of archegonia at the distinc'tive from Ginkgo biloba but in this feature the micropylar end the present taxon can be clearly former comes closer to Pinus laricio and P. syluestris. differentiated from the other genera, viz. Rugaspermum, Savitrispermum, Nidispermum, Rostrumaspermum uenkatachalae sp. nov. Pyrijormispermum, Pantiaspermum and PI. 1, figs 1-9, Text-fig. 1A-N Row ndasperm u m, reported from N idp ur Diagnosis-Seed ovate, platyspermic, outline fossiliferous beds. Further, in the nature of entire, measuring 2-3 mm in length and 1.5-2 mm in integument these taxa generally possess tough SRIVASTAVA & MAl"lIK-AN ARCHEGONIATE SEED FRO!'vl TRIASSIC 103 integument composed of varied cell shapes while in Triassic period. But certainly it can be inferred that R venkatacbalae the outer integument is extremely such coniferous traits must have been differentiated thin and delicate having irregular·shaped cells. during Triassic time because conifers were passing Archegoniate seeds whether preserved as through transitionaI stage during Early Mesozoic petrifaction or compression, markedly differ from R. (Bailey, 1933). Depiction of such pineaceous venkatacbalae in bearing distinct tentpole. Besides, features in Triassic seed supports the view of Meyen these archegonia bearing seeds completely lack (1974) that separation of modern conifers tOok place tubular neck and the archegonia can occasionally be at this stage. located in sunken state tOwards the micropylar end. The conspicuous absence of pollen chamber Callospermarion undulatum (Neely) Rothwell 1981 and free nucellus from integument at its apex alone comes closer to archegoniate seeds of Nidpur sufficiently strengthens the evidence for its in having tubular archegonia but the former at once relationship with coniferales. contrasts from the latter because of being anatOmically preserved form. In details of anatomy, ACKNOWLEDGHt1ENT the comparison berween R venkatacbalae and C undulatum is not possible because of the state of Authors are grateful to Professor D. D. Pant, preservation. Collospermum and Palaeocarpus Allahabad and Dr B A. Vagyani, Kolhapur for their described ,by Pant et at. (1985) from Lower useful sugge stions. Gondwana of India also differ from R venkatacbalae in having archegonia without tubular neck. REFERENCES Amongst the extant forms, in gymnosperms, there is a tendency of shortening of neck, and also Andrews, H N. 1949. Nucellangium, a new genus of fossil seeds archegonia are located in varied pOSition. Conifers preViously assigned to Lepidocmpon. Ann. Mo. bot. Gdn 36 : 479·506 have been exception where archegonia show a Andrews. H. N. 1961. Studies in Palaeobotany. Wiley. New York. lateral position; similarly Epbedra also shows Andrews, H. N. & Felix. C J. 1952. The gametophyte of Cardiocar· laterally placed archegonia. But tpbedra stands apart pus spinatlls Graham. Ann Mo. bol. Gdn 39: 127·136. from R venkatacbalae in having large neck. Bailey, L E. 1933. Problems in identifying the wood of Mesozoic However, R venkatacbalae bears a tubular neck and Coniferae. Ann BOI. 47(185) : 145·157 Benson. M. 1914. SpbaeroslOma ouale (Conostoma ouale et in this particular character it comes closer to Pinus i11lermedium, Williamson), a Lower Carboniferous ovule lan'cio and Pinus sylvestris (Foster & Gifford, 1974; from Pettycur, Fifeshire, Scotland. Trans R. Soc. £dinb. 50 : Sporne, 1974) where the rwo archegonia are 1·15. associated with a short tubular neck. Occasionally, in Brongniarr, A. 1881. Recherches sur les graines fossiles silicifiees, P sylvestris varying number of archegonia have also Paris Imprimerie Nationale: }·93. been noticed. Eggen, D. A & Delevoryas, T. 1960. Callospermarion, a new seed genus from the Upper Pennsylvanian of Illinois Phytomor· In general organization of apical portion of phology 10 : 323· 360. megaspore sac, R. venkatacbalae may be compared Foster, A. S & Gifford, E. E M. Jr 1974. Comparative morphology with Ginkgo biloba but in the latter, archegonia are of vascular plants. W. H. Freeman & Company, San Francisco. quite distinctive because of rudimentary neck Gould, R E. & Delevoryas, T. 1977. The biology of Glossopteris: Evidence from petrified seed·bearing and pollen·bearing (Maheshwari & Sanwal, 1963). Also, in C biloba the organs. Alcheringa 1 : 387·399. number of archegonia ranges from 2-4 while in the Graham, R 1935 Pennsylvanian flora of Illinois as revealed in present new seed only two archegonia have been coal balls II. BOI. Gaz. 97 : 156-16B. observed. Long, A. G. 1944. On (he prothallus of LagenoslOma ovo/des Will. Ann BOt. Lond NS 8 : 105·117 Affinity-The ongOing characteristics of the Long, A. G. 1959 On the structure of "Galymmatotheca kidston(' present taxon have led to the conclusion that its Calder (emended) and "Genomosperma latens" gen. et sp. relationship is closer to Coniferophytes nov. from the calciferous Sandstone Series of Bet,vickshire. (Coniferales) than the other plant groups. The Trans R. Soc. Edinb. 64 : 29·44 presence of archegonia with tubular neck settles its Long, A G. 1960. StamnoslOma bUlIonense gen. et sp. nov, a pteridosperm seed and cupule from the calciferous sand· affiliations with the extant species, Pinus laricio and stone series of Berwickshire. Trans R. Soc. £dinb. 64 : 201· P sylvestris. This resemblance is indicative of the 215. occurrence of Pinus-like plants in Nidpur flora. This Maheshwari, P. & Sanwal, M. 1963. The archegonium in gymnos· could be further substantiated by the findings of perms: A review. Mem. Indian bot Soc. 4 : 103· 119. needle-like compressions from the same strata. Manik, S R 19BB. Some new genera of Triassic seeds. Palaeo· botanisl 36: 197·200. However, this character is not suggestive that the Meyen, S. V. 1971. Parallelism and its significance for the sysle· family Pinaceae must have been originated during matics of fossil plants. GeopbylOlogy 1(1) : 34·47 104 THE PALAEOBOTANIST

Neely, r. E 1951. Small petrified seeds trom the Pennsylvanian tales). Curl' Sci. 48( 13) : 601. of Illinois BOI. Gaz. 113 : 165167 Sporne, K. R. 1974. Th8 morphology oj gymnosperms-Ihe Slruc· Pant, D. D.. Nautiyal, D. D. & Tiwari. S. R. 1985. On some Indian lure alld eo-olulion oj primilive seed planlS, pp. 1·216, Lower Gondwana compressions of seeds. Palaeonlographica Hutchinson & Co. Ltd, London. 196B 31·78 Stewart, \V. N. 1951. A new Pacbytesla from the Berryville locality Rothwell, G W. 1971 Ontogeny of the Paleozoic ovule, Callos· of south·eastern Illinois. Am. iVlidl. Nat 46: 717.742. permanon pusillum. Am. II BOI. 58(8) : 706·715. Stidd, B. M. & Cosentino, K. 1976. Nucellangium gametophytiC RothweJl, G. W. 1981 The Callistophytales (Pteridospermopsida): structures and relationship to Cordaites. BOI Gaz. 137: Reproductively sophisticated Paleozoic gymnosperms. Rev. 242-249 Palaeobol. Pa/l'no/. 32 103·121 Taylor, T N. & Millay, M. A 1979. Pollination biology and repro· Seward, A C. 1919 Fossil planls, III Cambridge Univ press, duction in early seed plants. Rev. Palaeobol. Palynol. 27 : Cambridge. 329355 Sharma, B D. 1979. Archegonia in Williamsonia Carr (Bennetti·