A revision of the genus Pandalus (Crustacea: Decapoda: Caridea: Pandalidae)

The genus Pandalus Leach, 1814, is revised based upon the abundant material from collections in various museums or institutions in the world. Altogether 20 species are recognized which appear to form five groups. Nineteen species are recognized in Pandalus, three of which are described as new: P. curvatus from southern Japan, and P. chani and P. formosanus from Taiwan. Four informal species groups are also recognized within the genus: P, montagui group (P. montagui Leach, 1814; P. borealis Kroyer, 1838; P. goniurus Stimpson, 1860; P. jordani Rathbun, 1902; P. tridens Rathbun, 1902; and P. eous Makarov, 1935); P. stenolepis group (P. stenolepis Rathbun, 1902; P. curvatus sp. nov.), P. hypsinotus group (P, hypsinotus Brandt, 1851; P. danae Stimpson, 1857; P. prensor Stimpson, 1860; P. gracilis Stimpson, 1860; P. gurneyi Stimpson, 1871; P. nipponensis Yokoya, 1933; P. teraoi Kubo, 1937; P. chani sp. nov., and P. formosanus sp. nov.): and P. platyceros group (P. platyceros Brandt, 1851; and P. latirostris Rathbun, 1902). The P. platyceros group appears to be most closely related to the genus Pandalopsis Bate, 1888, but Pandalus is retained as a possible paraphyletic group. Protandrous hermaphroditism is known in all but two species of the genus (P. curvatus and P. formosanus), for which only specimens of either male or female have been available. Pandalus propinqvus G. O. Sars, 1870, is transferred to a new monotypic genus Atlantopandalus, because of its lack of hermaphroditism and possession of some unique morphological characters, including one indicating a close relationsip to Dichelopandalus Caullery, 1896. All species are fully described and illustrated. The affinities and important morphological variations of the species are discussed. A key for adults is presented for the identification of the species. Biogeography of the genus is briefly discussed.