Hemigaleus Bleeker

William T. White, Peter R. Last & Leonard J. V. Compagno, 2005, Description of a new species of weasel shark, Hemigaleus australiensis n. sp. (Carcharhiniformes: Hemigaleidae) from Australian waters., Zootaxa 1077, pp. 37-49 : 37-38

[[ Hemigaleus Bleeker ]]

The genus Hemigaleus , proposed by Bleeker (1852) for Hemigaleus microstoma from Java, presently consists of only one described species. Hemigaleus microstoma is widely distributed in the Indo-West Pacific from southern India and Sri Lanka in the west, to Myanmar, Thailand, Indonesia (Java), Taiwan, China and the Philippines in the east (Compagno, 1984, 1988, 1998). This species was also previously documented as occurring widely across northern Australia (Compagno, 1984), and off Papua New Guinea (Last and Stevens, 1994). Stevens and Cuthbert (1983) documented substantial differences in tooth and vertebral counts between Australian specimens and material from Singapore, Thailand and Indonesia (see also Compagno, 1988). These authors provisionally identified the Australian form as H. microstoma but stated that a revision of the genus should be undertaken in the future once specimens were collected from other areas. Similarly, Compagno (1988) treated Hemigaleus temporarily as a monotypic genus, but stated that the observed differences between the specimens could be elucidated once more specimens were examined from other regions. Last and Stevens (1994) highlighted the need for a comparison of material from across the Indo-Pacific region to explain morphological differences in Hemigaleus populations. Compagno (1999) stated that differences in coloration and meristics suggest that the Australian species may be a separate taxon and he treated the two separate forms in the key to species, i.e. Hemigaleus microstoma and H. sp. aff. “microstoma” .

Recent market surveys in eastern Indonesia produced a variety of sharks, skates, rays and chimaeras. Amongst this material were a number of individuals of Hemigaleus microstoma . These specimens have allowed a more detailed comparison between the Australian and Indonesian samples and have confirmed that the Australian Hemigaleus is a separate species from H. microstoma . This new species is described below.