Shells of Songkhlanaia species A, B topotype of S. tamodienica from Tamot Stream, Songkhla Lake Basin, Thailand A adult specimen MUMNH-UNI2956 and B young specimen MUMNH-UNI2971 C–F S. moreleti C syntype MNHN-IM-2000–34623 from Mekong Basin, Cambodia, with original labels D syntype of Pseudodon thomsoni Morlet, 1884, MNHN-IM-2000-1800 from Mekong Basin, Cambodia, with original labels E adult specimen MUMNH-UNI0301, and F young specimen MUMNH-UNI3428 from Phrom Hot Stream, Tonle Sap Basin, Thailand. Photographs C, D M. Caballer (2019, MNHN Project: RECOLNAT No. ANR-11-INBS-0004).