The Recognition and Molecular Phylogeny of Mugilogobius mertoni Complex (Teleostei: Gobiidae), with Description of a New Cryptic Species of M. flavomaculatus from Taiwan

(Weber, 1911) is considered as a widely distributed species around the Indo- West Pacific region, and several nominal species are considered as junior synonyms of . However, in our recent study, several different morphological types of were observed, they were collected from Taiwan, Palau and Phuket Island. This study aimed to investigate the taxonomic status of those -like individuals, we also attempted to assess their phylogenetic relationship base on combined mitochondrial DNA ND5, Cyt and D-loop sequences. The present morphological and molecular evidences suggested that the current could be regarded as a species complex, and several cryptic species might be included in complex. One of these which collected from Taiwan is described as a new species, n. sp. based on both morphological and molecular evidence in this study. The phylogenetic tree also revealed that n. sp. is the closest to . n. sp. and its sister species are found to have different niches in the same estuary. Moreover, stable morphological characters and nuclear gene RAG2 also clearly show that no hybridization is detected in between n. sp. and . Except the present new species, taxonomic status of all junior synonyms refers to are also discussed.