Die Ostracodengattung Hyperchilarina und das Aparchites-Problem

The genus Hyperchilarina — hitherto known only from North America — is fairly common in the Ordovician of Europe. A detailed description is given from published and new material. The most remarkable feature of the genus — the adventral row of spines on the smaller left valve — is considered as a homologon of the velum of the Palaeocopa. The hypothesis is stated that the main adventral structures of the Palaeocopa — the velum and the marginal structure — were originally structures of the contact margin, and an evolution model is given. Hyperchilarina is possibly identical with Aparchites. It seems that at least both belong to one family. The Aparchitacea are considered as a new sub-order (Leiocopa) on their own, beside the Palaeocopa, because of the missing antral and cruminal dimorphism and the original features of Hyperchilarina. In the course of the description, three new species are established.