Review of the mudflat varunid crab genus (Crustacea, Brachyura, Varunidae) from East Asia and northern Vietnam.

Intertidal mudflat crabs of the genus H. Milne Edwards, 1852 (Crustacea: Brachyura: Varunidae) from China, Taiwan, and northern Vietnam are taxonomically revised by morphological and molecular evidence. These crabs show sexual dimorphism and morphological variation of a considerable range in the infraorbital ridge, one of the primary features previously used for species identification. In this study, four species were identified from the region: De Man, 1888; Stimpson, 1858; Gordon, 1930; and Tweedie, 1950. Based on the results of the morphological examination, and as confirmed by molecular evidence from mitochondrial cytochrome oxidase subunit I (COI), taxonomic confusion surrounding was resolved, and Sakai, 1939, is considered a junior synonym of . The geographical distribution of extends along the shores of China, north to Jiangsu, whereas the Southeast Asian was newly recorded from northern Vietnam and Hong Kong.