Two New Species of Eretmophyllum (Ginkgoales) from the Jurassic of Eastern Siberia

Two new species of Eretmophyllum Thomas are described from the lower (Toarcian) and upper (Aalenian) Prisayan Formation of the Irkutsk Basin, Eastern Siberia, Russia based on distinct morphological and cuticular features of the leaves that distinguish them from other species of the genus. Eretmophyllum polypapillosum sp. nov. is characterized by the presence of 2-3 papillae on the lower and upper epidermis of ordinary cells. Taphonomically, the leaf burials of E. polypapillosum sp. nov. indicate that it preferred mesophilic forests developed on river terraces and/or low watersheds. Eretmophyllum yershowskiensis sp. nov. is represented exclusively by leaf cuticles extracted by coal maceration, and it probably inhabited the low banks of peat bogs. The presence of the genus Eretmophyllum in the Early Jurassic of France and Eastern Siberia shows that it was already widespread in the territory of Eurasia, distributed from Western Europe to Eastern Siberia. This indicates the possible existence of Eretmophyllum species elsewhere in the Early Jurassic such as Central Asia and Northwest China.

Automated summary

Two new Eretmophyllum Thomas species were identified in the Prisayan Formation in the Irkutsk Basin, Eastern Siberia, Russia, based on distinct morphological and cuticular features. E. polypapillosum sp. nov. prefers mesophilic forests on river terraces and/or low watersheds, while E. yershowskiensis sp. nov. is found exclusively in peat bogs.