Early Cretaceous ribbed aptychi – a proposal for a new systematic classification

Abstract

The older system for classification of ribbed calcareous Early Cretaceous aptychi consisted of two genera: Punctaptychus and Lamellaptychus. Later, I. Turculet divided Lamellaptychus into several subgenera. Within the framework of both the genera, species and subspecies were distinguished, which resulted in binominal and trinominal nomenclature. With regard to the richness of newly described species and subspecies in recent years, is not possible to continue using the original system. It is the basic ribbing that plays the decisive role in the generic and subgeneric classification of ribbed aptychi. In the case of subspecies systematics, all details on the valve surface are used with the exception of the sigmoidal bend (fractocostatus) and radial lines (radiatus). The ribbed aptychi are newly divided into the following families: Punctaptychidae fam. nov. and Lamellaptychidae fam. nov. Within the family Punctaptychidae we are able to distinguish two genera: Punctaptychus Trauth, 1927 and Cinctpunctaptychus gen. nov. The family Lamellaptychidae includes five genera differing in the basic arrangement of the ribs: Lamellaptychus Trauth, 1927, Beyrichilamellaptychus Turculet, 1994, Mortilletilamellaptychus gen. nov., Thorolamellaptychus Turculet, 1994 and Didayilamellaptychus Turculet, 1994. Eight species and one subspecies are established as new: Cinctpunctaptychus undulatus, Beyrichilamellaptychus pseudostuderi, Mortilletilamellaptychus mortilletioides, M. submortilleti noricus, M. stanislavi, Didayilamellaptychus hennigi, D. andrusovi and D. renzi.