Tachysurus taeniatus (Günther, 1873), a senior synonym of the congeneric species T. ondon (Shaw, 1934) (Teleostei, Bagridae) from eastern China

Despite the current recognition of <i>Tachysurustaeniatus</i> and <i>T.ondon</i> as two separate valid species of China, neither species have been revised based on examination of their types and/or topotypical materials, nor have they genetically analyzed. In this study, examination of the holotype of <i>T.taeniatus</i> showed that it has a serrated anterior edge of the pectoral spine, a slightly emarginate caudal fin, and longer maxillary barbels extending beyond the base of the pectoral spine, the characters shared with specimens currently identified as <i>T.ondon</i>. Morphological comparisons and molecular analysis showed that specimens from mainland China, which are characterized by the three mentioned morphological features, represent a single species. According to the nomenclatural rule of priority, <i>T.taeniatus</i> is a senior subjective synonym of <i>T.ondon</i>. Within this concept, <i>T.taeniatus</i> is widely distributed in the lower reaches of Yangtze River and coastal rivers in Zhejiang and Fujian Province and closely related to <i>T.aurantiacus</i>, which is endemic to Japan. The morphological differences and species-level genetic distance between <i>T.taeniatus</i> and <i>T.aurantiacus</i> provide additional support for synonymization of <i>T.taeniatus</i> and <i>T.ondon</i>. The paper also describes ontogenetic color changes and coloration polymorphism in this species. Phylogeny of the <i>T.aurantiacus</i> group, to which <i>T.taeniatus</i> belongs, is also discussed.