A NEW, RIBBED SPECIES OF NEMKOVELLA LESS 1987 (DISCOCYCLINIDAE), AND DISCUSSION OF THE GENUS ACTINOCYCLINA GUMBEL, 1870

A new species of the genus Nemkovella (Nemkovella rota n, sp,) is desc ribed from the early Cuisian (early Eocene) of southern France, The pr esence of a discocy-clinid-type microspheric juvenarium and the absenc e of annular stolons permit this generic assignation. The most distinc tive characteristic of this new species is the presence of numerous sm all ribs. Orthophragminid (Discocgclinidae and Orbitoclypeidae) specie s with numerous small ribs have been traditionally assigned to the gen us Actinocyclina Gumbel 1870. However, different species of both Disco cyclina and Nemkovella, as well as other orthophragminid genera such a s Pseudophragmina and Orbitoclypeus, also have ribs as a specific char acter. Because Actinocyclina is characterized exclusively by the prese nce of ribs, and this is a specific character common to several genera , then Actinocyclina must be considered invalid. Moreover, because the generotype of Actinocyclina has a discocyclinid-type microspheric juv enarium and annular stolons, it is herein reassigned to the genus Disc ocyclina as a ribbed species, D, radians (d'Archiac).