Revision of the Genus Rhyacichthys Using Integrative Taxonomy

Abstract: The rivers of tropical islands are colonized by amphidromous species. The order Gobiiformes presents the major diversity in these teleost communities. The genus Rhyacichthys forms a particular group within this order, with the presence of several plesiomorphic characters but also because it constitutes the sister group of all other Gobiiformes. The genus Rhyacichthys includes two valid species: Rhyacichthys aspro (Valenciennes, 1837) and Rhyacichthys guilberti Dingerkus & Séret, 1992 which are only found in the western Pacific (e.g., Vanuatu, Indonesia, Japan). The aim of the present study consists of the taxonomic revision of the genus, in which more than two species are suspected, using integrative taxonomy. Morphomeristic and molecular analyses (partial mtDNA, 7134 bp) were conducted on recent and collection specimens, including type specimens. Short fragments of mtDNA (<130 bp) were obtained for type specimens of R. aspro and R. guilberti. These results allowed us to highlight morphological and genetical differences between the two valid species and to resurrect a third one. This integrative approach helped to clarify relations within the genus and its distribution range with a better understanding for this poorly studied group.