Revision of the genus Grenana Samylina from the Middle Jurassic of Angren, Uzbekistan

The revision of the material from the Middle Jurassic sediments of Angren (Uzbekistan), comprising leaves, collar complexes, and seeds originally described together as a new putative pteridosperm genus Grenana Samylina (1990), suggests a ginkgoalean affinity of these plant remains. Morphological and epidermal characters of Grenana leaves fit the diagnosis of Sphenobaiera Florin, on the basis of which a new combination Sphenobaiera angrenica comb. nov. is designated, turning the generic name Grenana into a younger synonym of Sphenobaiera. “Grenana” collar complexes, considered by Samylina to represent ultimate leaf segments with terminal cupules, are reinterpreted as compound generative axes consisting of peduncles, pedicels, and collars, and similar to female fructifications of the modern and fossil Ginkgo L. A new genus Nagrenia gen. nov. and species Nagrenia samylinae sp. nov. are erected to accommodate this kind of remains. It is confirmed that leaves and collar complexes share a similar epidermal pattern and thus likely represent parts of the same plant. Seeds of three types, all with characteristic ginkgoalean structure, are discovered in association with the leaves of S. angrenica comb. nov. Two kinds of seeds are placed within Allicospermum Harris and one in Ginkgo; a new species Allicospermum angrenicum sp. nov. is described.