Eostangeria ruzinciniana (Zamiaceae) from the Middle Miocene of Bulgaria and its relationship to similar taxa of fossil Eostangeria, and extant Chigua and Stangeria (Cycadales)
by Uzunova K., Palamarev E., Kvacek Z. (2001)
KRASSIMIRA UZUNOVA1, EMANUEL PALAMAREV2 and ZLATKO KVACˇ EK3
1 Biological Faculty, Sofia University, 8 Dragan Znakov, 1421 Sofia, Bulgaria
2 Institute of Botany, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev, 1113 Sofia, Bulgaria,
3 Charles University, Faculty of Science, Albertov 6, 128 43 Praha 2, Czech Republic
by Acta Palaeobot. 41(2): 177–193 –
Characterisation of Eostangeria ruzinciniana (Palamarev, Petkova & Uzunova) Palamarev & Uzunova(Middle Miocene – Volhynian, Bulgaria) is augmented. The species is compared with morphologically similar
cycads: E. saxonica Barthel (Eocene of Germany), E. pseudopteris Z. Kvacˇek & Manchester (Late Palaeocene and Eocene of western USA), and the extant Chigua D. Stevenson and Stangeria T. Moore. Leaf epidermal anatomy indicates that E. ruzinciniana is closely related to other members of Eostangeria, forming with them a natural unit. Eostangeria slightly differs from Chigua (Zamioideae) in the presence of short dark-staining cells in the lower epidermis, densely toothed margins, and in the case of Eostangeria ruzinciniana by obviously persistent, non-articulated leaflets. In morphological features of the leaflets, Eostangeria resembles Stangeria (Stangeriaceae); however, the latter decidedly differs in entirely cyclocytic stomata lacking ventral lignified lamellae, coarsely striated epidermis with strongly undulate anticlines and an absence of short dark-staining cells.
A new subfamily Eostangerioideae is suggested to accommodate Eostangeria within Zamiaceae.