Revision of Some Eocene Charophytes from the Zaysan Basin, Eastern Kazakstan

Abstract

New collections of Eocene charophytes from the Zaysan basin of eastern Kazakstan allow taxonomic revision of some previously reported species. Sphaerochara zajsanica Gluchovskaya, 1984, reassigned as Peckisphaera zajsanica (Gluchovskaya) comb. nov., from the middle Eocene, is the oldest Palaeogene charophyte known from the Zaysan basin. The Lychnothamnus formosus group from the upper Eocene encompasses gyrogonites previously assigned by Kyansep-Romashkina (1980) to Amblyochara orbae, Rhabdochara formosa, Rhabdochara septata, Harrisichara aff. subteres and Harrisichara connexae.