The genus Fryopsis Wolfe (al. Cardiopteris Schimper): A taxonomic revision

The classification of Mississippian compression remains is often problematic due to poor definitions of genera and unclear delimitation of individual species.The name of the Mississippian genus Cardiopteris Schimper 1869 is a homonym of Cardiopteris Wallich ex Royle 1834 and was replaced by the name Fryopsis Wolfe 1962. However, the new name was only introduced for Fryopsis polymorpha, which was designated as type species. The other species assigned to Cardiopteris Schimper never have been transferred formally to Fryopsis. A conspecifity of Fryopsis polymorpha, Cardiopteris frondosa and Cardiopteris hochstetteri has often been discussed but never been proven.In this contribution the distinctive characters described in the literature for the three “species” – primarily size, position, and form of the pinnules – are reviewed critically. Morphometric analyses of previously described specimens and a substantial number of unpublished ones show that there are no distinct differences in leaf size. Moreover, alternate pinnules are not restricted to Cardiopteris hochstetteri as was previously thought, and individual “species” are not characterized by a typical leaf shape. Thus, a distinction into different species cannot be maintained. Cardiopteris frondosa and Cardiopteris hochstetteri are conspecific with Fryopsis polymorpha. Most of the other species described in Cardiopteris belong to other genera, have been recognized as synonyms of other taxa, or have to be regarded as species dubiae. Cardiopteris altaicus Radčenko 1985 is formally transferred to Fryopsis.

► The species of Cardiopteris Schimper are critically reviewed.
► Cardiopteris frondosa and C. hochstetteri are added to Fryopsis (al. Cardiopteris) polymorpha.
► Cardiopteris altaicus is transferred to Fryopsis Wolfe.
► Other Cardiopteris-species are synonyms, species dubiae or belong to other genera.