Mollusc species from the Pontocaspian region - an expert opinion list Author Wesselingh, Frank Naturalis Biodiversity Center, Leiden, Netherlands Author Poorten, Jan Johan ter Field Museum of Natural History, Chicago, United States of America Author Kijashko, Pavel Moscow State University, Moscow, Russia Author Albrecht, Christian Justus Liebig University, Giessen, Germany Author Anistratenko, Olga Yu Schmalhausen Instite of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine & Institute of Geological Sciences, National Academy of Sciences of Ukraine, KievUkraine Author Frolov, Pavel Saint-Petersburg State University, Saint Petersburg, Russia Author Gándara, Alberto Martinez Grigore Artipa National Museum of Natural History, Bucharest, Romania Author Gittenberger, Arjan Gittenberger Marine Research, Inventory & Strategy, Leiden, Netherlands Author Gogaladze, Aleksandre Naturalis Biodiversity Center, Leiden, Netherlands Author Mikhail Karpinsky Russian Federal Research Institute of Fisheries and Oceanography, Moscow, Russia Author Popa, Luis Grigore Antirpa National Museum of Natural History, Bucharest, Romania Author Sands, Arthur F Justus Liebig University, Giessen, Germany Author Vandendorpe, Justine Justus Liebig University, Giessen, Germany Author Wilke, Thomas Justus Liebig University Giessen Germany text ZooKeys 2019 827 31 124 http://dx.doi.org/10.3897/zookeys.827.31365 journal article http://dx.doi.org/10.3897/zookeys.827.31365 1313-2970-827-31 10B663895E424E5287D8F49E2405D651 10B663895E424E5287D8F49E2405D651 Didacna longipes (Grimm, 1877) *1877 Cardium longipes Grimm: 54-56, pl. 8, fig. 4 a-c . 1952 Didacna longipes (Grimm, 1877). - Zhadin: 349-350, fig. 326. 1969 Didacna longipes (Grimm). - Logvinenko and Starobogatov: 326, fig. 345. 1973 Didacna longipes Grimm, 1877. - Grossu: 132, text fig. 9, pl. 1, fig. 2. ?2007 Didacna carinata Nevesskaja: 943, pl. 24, figs 15-19. 2013 Didacna longipes (Grimm, 1877). - Kijashko in Bogutskaya et al.: 354, fig. 137, photo 43. 2016 Didacna longipes (Grimm, 1877). - Vinarski and Kantor: 71. Status. Pontocaspian species, endemic to Caspian Sea. Figure 4. Lectotype Dreissena rostriformis versus D. grimmi . a D. rostriformis Deshayes, 1838. Lectotype. Pliocene, Crimea. Reproduced from Archambault-Guezou (1976, pl. 6, fig 2a-2c) b RGM.961901, D. grimmi (Andrusov, 1890). Caspian Sea offshore Aktau, Kazakhstan, sample KAZ17-21, depth 44.3 m. Scale bar: 1 cm. Type locality. Caspian Sea, offshore Azerbaijan, approximately 40°39'N , 50°26'E . Distribution. Southern and middle Caspian Sea basins and southern part of the northern Caspian Sea down to 30-40 m water depth. The species often co-occurs with D. barbotdemarnii . Remarks. We are uncertain about the status of Didacna carinata Nevesskaja, 2007. The overall outline resembles that of D. barbotdemarnii , but the former species appears smaller and thinner. Kijashko in Bogutskaya et al. (2013) considered D. carinata as a synonym of D. longipes . Conservation status. Not assessed.