01756nas a2200133   4500008004100000245007900041210006900120490000700189520132200196100002101518700002101539700001801560856004401578       2016                        eng d00aMegaspores of an early Miocene aquatic lycopod (Isoetales) from Antarctica0 aMegaspores of an early Miocene aquatic lycopod Isoetales from An0 v553 aThe paucity of late Paleogene and Neogene floras from Antarctica limits our ability to understand the interplay between Antarctic climate evolution and the impact that glaciation had on the vegetation, in particular, how the vegetation changed from temperate Eocene forests, to today’s sparse vegetation. Fluvial and lacustrine strata deposited in a wet-based glacial sequence (Friis Hills, McMurdo Dry Valley sector, Transantarctic Mountains) have yielded abundant megaspores. These strata are early Miocene based on correlation with a volcanic ash dated at 19.76 ± 0.11 Ma. The megaspores are up to 736 μm in diameter with well-developed wing-like laesurae and equatorial zona. The morphology is consistent with extant Isoetes, and demonstrates the presence of Lycopsida and the Isoetaceae within Antarctic Miocene floras. Today, Isoetes is widespread from the Tropics to the Arctic such as Greenland (I. echinospora, I. lacustris) and from marginal marine (I. ekmanii) to high altitudinal environments (I. lechleri), though commonly associated with lacustrine or aquatic environments. The fossil spores occur in fluvial and lacustrine beds, suggesting the parent plants were aquatics. The occurrence together with mosses and Nothofagus leaves points to persistent vegetation in the early Miocene of Antarctica.1 aCantrill, D., J.1 aAshworth, A., C.1 aLewis, A., R.  uhttps://isoetes.myspecies.info/node/233