Umkomasia (megasporophyll): part 1 of a reassessment of Gondwana Triassic plant genera and a reclassification of some previously attributed

Abstract

Anderson, H.M., Barbacka, M.K., Bamford, M., Holmes, W.B.K. & Anderson, J.M., 8 February 2019. Umkomasia (megasporophyll): Part 1 of a reassessment of Gondwana Triassic plant genera and a reclassification of some previously attributed. Alcheringa 43, 43–70. ISSN 0311-5518.

The genus Umkomasia, a megasporophyll, belonging to the pteridosperms (seed ferns) in the family Umkomasiaceae (Corystospermaceae), is reassessed comprehensively worldwide. All previous records are analysed. Certain fertile structures previously attributed are reclassified. Umkomasia is shown to be restricted to the Triassic of Gondwana where it is associated with the genus Pteruchus, a microsporophyll, and the genus Dicroidium, a vegetative leaf. It is well represented from Argentina, Australia and southern Africa where the Molteno Formation is by far the most comprehensively sampled with eight species described. Two specimens from the upper Permian of India attributed to Umkomasia are reclassified as cf. Arberiopsis sp. A whorled fertile structure from Antarctica, previously assigned to Umkomasia, is reclassified in a new genus as Axsmithia uniramia. Another compression fossil and the permineralized Umkomasia resinosa remain as valid records from Antarctica. The material described as Umkomasia from the Triassic of China is reclassified as Stenorachis asiatica. The Lower Jurassic record from Germany is placed in a new genus as Kirchmuellia franconica. The records of Umkomasia sp. from the Rhaetic of Germany are reclassified as cf. Kirchmuellia sp. and the single specimen from the Jurassic of Libya as genus et sp. indet. The Lower Cretaceous record from Mongolia has been reclassified by other researchers as Doylea mongolica. A pictorial key to Umkomasia species is provided, geographic and stratigraphic distributions are tabulated.

Heidi M. Anderson, [[email protected]], Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa; Maria Barbacka [[email protected]] W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, Kraków 31-512, Poland, Botanical Department, Hungarian Natural History Museumartmem H-1431, Budapest, Pf. 137, Hungary; Marion K. Bamford [[email protected]] Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa; W. B. Keith Holmes [[email protected]] 46 Kurrajong Street, Dorrigo, NSW 2453, Australia, University of New England, Armidale, NSW 2351, Australia; John M. Anderson [[email protected]] Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 20150, South Africa.

Key words:

• Triassic
• Gondwana
• Molteno Flora
• Umkomasia
• Dicroidium
• corystosperms

Acknowledgements

We acknowledge the DST-NRF Centre of Excellence in Palaeosciences for a research grant to Marion Bamford and a travel grant to Heidi Anderson. Maria Barbacka was supported by the W. Szafer Institute of Botany, Polish Academy of Sciences from their statutory funds. We appreciate the help of Andrew Rozefelds, Mary Dettmann and Trevor Clifford at the Queensland Museum for assistance in locating specimens and discussion. We thank Hannes Du Plessis and Clara Anderson for technical assistance in the preparation of this manuscript. Two anonymous reviewers are thanked for their helpful comments.

Permission has been obtained for the use of the figures from the corresponding authors and the publishers (permission date and/or license number included) as listed: Axsmith et al. (2000, figs 4, 11, 13, text-fig. 21), American Journal of Botany, Botanical Society of America, publisher: John Wiley and Sons (31/1/18); Chandra et al. (2008, fig. 2A, C), Palaeontology, The Palaeontological Association, publisher: John Wiley and Sons (3/1/2018); Kirchner & Müller (1992, pl. 1, fig. 1), Palaeontographica B, publisher: Schweizerbart (11/12/2018); Lejal-Nicol & Klitzsch (1975, fig. 8.10) Geologishe Rundschau, publisher: Springer Nature (license number 4247511005313); Shi et al. (2016, fig. 1b, d), New Phytologist, publisher: John Wiley and Sons (license number 4250220414562); Zan et al. (2008, pl. 1, figs 1, 4) Review of Palaeobotany and Palynology, publisher: Elsevier (15/2/2018).

Disclosure statement

No potential conflict of interest was reported by the authors.