New Middle Jurassic-Lower Cretaceous bivalves from southern Tibet

Bivalves form a significant proportion of the Middle and Upper Jurassic marine fauna of southern Tibet, with an upwards increase in diversity followed by drastic reduction in the Lower Cretaceous. Faunas are typically Tethyan. Systematic study of collections from Nyalam, Gamba and Jiangzi districts allows the establishment of new genera Venustas and Yoldioides in the Malletiidae and Antipectenoides in the Pectinidae and 13 new species in the following genera: Nuculoma, Mesosaccella, Grammatodon (Indogrammatodon), Oxytoma, Meleagrinella, Entolium, Ctenoides, Anisocardia and Protodiceras.