A new species of the thorid shrimp genus Heptacarpus Holmes, 1900 (Decapoda: Caridea) from Japan

A new species of the thorid shrimp genus Heptacarpus Holmes, 1900, H. elatus, is described and illustrated based on two specimens collected from off Shimoda, Izu Peninsula, central Japan, at sublittoral depth of 42– 46 m. It belongs to the species group with an epipod only on the third maxilliped (absent on the first to third pereopods) and is distinguished from the other members of the group by the prominent, roundly triangular boss on the third pleomere tergite, the clearly marked median lobe on the posterior margin of that somite and the unarmed fifth pleuron.

Morphological similarities are seen between the new species and H. geniculatus (Stimpson, 1860) and H. longirostris (Kobjakova, 1936). Phylogenetic analysis using the mitochondrial 16S rRNA gene supports the recognition of the present new taxon. Heptacarpus is now represented by 35 species, all occurring in the North Pacific Ocean.