Abstract:

Abstract Trapezidens Bolotov, Vikhrev & Konopleva, 2017 (Bivalvia: Unionidae: Lamellidentini) is a peculiar freshwater mussel genus, the range of which is confined to the Western Indochina Subregion (Myanmar). Here we show that this genus contains five allopatric species: Trapezidens angustior (Hanley & Theobald, 1876) from the Bago, Sittaung, and Bilin rivers; T. dolichorhynchus (Tapparone-Canefri, 1889) from the Ayeyarwady River; T. exolescens (Gould, 1843) from the Dawei River; T. scutum (Sowerby, 1868) from the Tanintharyi (Great Tenasserim) River; and T. yeti sp. nov. from the Ye River. Phylogenetically, Trapezidens angustior, T. dolichorhynchus, and T. yeti sp. nov. are closely related to each other, forming a species complex, while T. exolescens and T. scutum represent the most distant lineages within the genus. An updated synonymy for each species is compiled. References Bolotov, I.N., Kondakov, A.V., Vikhrev, I.V., Aksenova, O.V., Bespalaya, Y.V. Gofarov, M.Y., Kolosova, Y.S., Konopleva, E.S., Spitsyn, V.M., Tanmuangpak, K. & Tumpeesuwan, S. (2017a) Ancient river inference explains exceptional Oriental freshwater mussel radiations. Scientific Reports, 7, 1–14.

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