Taxonomic revision of the Late Cretaceous canaliculate radiolitid genera (rudist bivalves) Balabania Karacabey-Öztemür, Branislavia Sladić-Trifunović and Klinghardtites Lupu from Turkey, Serbia and Romania

Abstract

The genera Balabania Karacabey-Öztemür, Branislavia Sladić-Trifunović and Klinghardtites Lupu have previously been referred to as three new canaliculate radiolitid taxa. Well-preserved articulated shells of these rudist genera collected from eastern Turkey, Serbia and western Romania have now been re-examined and compared with the rudist literature. They have pallial canals in the originally aragonitic inner shell layer of the left valve flanking the cardinal apparatus and a long ligamental ridge, which are the diagnostic characteristics of Colveraia Klinghardt. As a result, two species are recognised here, namely Colveraia acuticostata (Karacabey-Öztemür), encompassing all species of Balabania and Colveraia bacevicensis (Milovanović) for all species referred to Branislavia. Klinghardtites musculosus (Klinghardt) is herein regarded to be synonymous with Colveraia darendeensis Karacabey. The left valve of Colveraia acuticostata is cap like with an eccentric apex inclined gently or strongly towards the dorsal side and overlap with the commissure and has flat or rarely slightly concave radial bands. Colveraia bacevicensis is characterised by deeply concave radial bands, and longitudinal ribs and grooves of the right valve, both of which are crossed by strongly folded growth lines that overlap each other and present distinct undulations on the surface of the valve. Ornamentation of the valve and the structure of the radial bands distinguish them from Colveraia variabilis Klinghardt and C. darendeensis Karacabey. Our re-examination of specimens previously described as Balabania acuticostata Karacabey-Öztemür from eastern Serbia shows that these can be included in C. darendeensis. A biogeographical overview of species of Colveraia in the Mediterranean Tethys is presented.