Taxonomy and mitochondrial sequence evolution in non-diadromous species of Rhinogobius (Teleostei: Gobiidae) of Hainan Island, southern China

Collections of the West-Pacific freshwater gobiid genus, Rhinogobius Gill, 1859, from Hainan Island, southern China, were examined morphologically and their taxonomic status revised according to meristic criteria and colouration. As well as a confirmation of the presence of R. leavelli, a further four species with a non-diadromous life history are here described as new to science under the following names: Rhinogobius changjiangensis n. sp., R. linshuiensis n. sp., R. nandujiangensis n. sp., and R. wangchuangensis n. sp., inhabiting different river basins on the island. To compare taxonomic status and evolutionary history of these species with Chinese freshwater species of Rhinogobius, the complete mitochondrial control region was amplified and sequenced for three of the new species, a non-diadromous species from southern China (R. duospilus), and two amphidromous species, R. leavelli from southern China (including Hainan) and R. maculafasciatus from Taiwan. The resulting molecular data indicate a high level of genetic divergence between these putative morphological species, and the phylogenetic reconstructions from both distance and discrete methods suggest that the endemic non-diadromous species of Hainan evolved from a common non-diadromous ancestor, probably during more than one period of marine regression.