The Genus Keppleritiana gen. nov. (Stephanoceratidae, Ammonoidea) from the Upper Bajocian of the Northern Caucasus
A new ammonite genus of the subfamily Garantianinae, family Stephanoceratidae, from the Upper Bajocian Strenoceras niortense Zone in the Bolshoi Zelenchuk River basin (Karachay-Cherkessia), with two new species from two different localities, is established. The type species Keppleritiana rostovtsevi gen. et sp. nov. is homeomorphic to some species of the Upper Bathonian-Lower Callovian genus Kepplerites (Fam. Kosmo-ceratidae) but is distinguished by the presence of a ventral furrow in adults. An isolated valve of an aptychus possibly belonging to this species is illustrated. Keppleritiana graebensteini sp. nov. has a more archaic morphology and is apparently ancestral to the type species. The macroconchs and microconchs of both species are described.