Diversity and Distribution of Fiddler Crabs (Crustacea: Brachyura: Ocypodidae) in Vietnam.

Based on recently collected material and records in the literature, 14 species of fiddler crabs (Crustacea: Ocypodidae: Gelasiminae) are reported from Vietnam. DNA barcoding analyses using the mitochondrial gene COI (cytochrome c oxidase subunit I) was performed to identify examined materials and their precise distributional range. Thirteen species-level taxa are identified and, with the exception of Galsimus borealis and G. vocans, have minimum interspcific divergences of at least 7.27%. The identified species include seven species of Tubuca Bott, 1973, three of Austruca Bott, 1973 and three of Gelasimus Latreille, 1817, and one Paraleptuca Bott, 1973. Two new records of Vietnam are herein reported: Tubuca rhizophorae and T. dussumieri. The southernmost distribution limits of East Asian G. borealis, T. acuta and T. arcuata are in northern Vietnam, A. lactea in central Vietnam, whereas northernmost limit of Southeast Asian T. rhizophorae and T. forcipata in southern Vietnam. A dichotomous key to identify the 14 Vietnamese species is provided.

Tropical sand-bubblers heading north? First discovery of Scopimera curtelsona Shen, 1936 (Crustacea: Decapoda: Dotillidae) populations in Hong Kong: possible range expansion from Hainan, China.

A sand-bubbler crab, Scopimera curtelsona Shen, 1936, previously known only from Hainan, China, is reported from Hong Kong. By searching past taxonomic records and examining local material, an increasing trend of S. curtelsona abundance was observed in comparison with another common sympatric dotillid, S. intermedia Balss, 1934, in Hong Kong since the early 2000s. This scenario is hypothesized to represent a northward range expansion of this tropical species from Hainan, China, by 500 km, coinciding with an increase in sea surface temperatures in Hong Kong, which are now at comparable levels with previous type locality temperatures. At a smaller scale, S. curtelsona was sympatric with two other dotillids: S. intermedia and Dotilla wichmanni De Man, 1892, on local sandflats, where the three species occupied different zones along the tidal gradient possibly due to the interaction between the variation in sediment characteristics and the crabs' maxillipedal setation.

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

Intertidal mudflat crabs of the genus Metaplax 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: M. elegans De Man, 1888; M. longipes Stimpson, 1858; M. sheni Gordon, 1930; and M. tredecim 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 M. longipes was resolved, and M. takahasii Sakai, 1939, is considered a junior synonym of M. longipes. The geographical distribution of Metaplax longipes extends along the shores of China, north to Jiangsu, whereas the Southeast Asian M. tredecim was newly recorded from northern Vietnam and Hong Kong.

From an Old Eroded Carapace: Rediscovery of the Majid Crab Leptomithrax sinensis Rathbun, 1916 (Crustacea, Brachyura, Majidae) from Taiwan and Japan.

Kingsley J. H. Wong, Peter K. L. Ng, and Ming-Shiou Jeng (2018) The majid crab Leptomithrax sinensis Rathbun, 1916 was previously only known from the holotype, a detached and partially eroded carapace collected during the Albatross Philippine Expedition in 1908 from the northern part of the South China Sea. Recent collections of fresh material from precious coral harvest sites off northeastern Taiwan, and Shikoku, Japan made verifying this poorly known species possible. The species is considered to be valid and is here redescribed, illustrated, and compared with its closest East Asian congener, L. bifidus (Ortmann, 1893).