First record and a new species of Alvinocaris Williams & Chace, 1982 (Crustacea: Decapoda: Caridea: Alvinocarididae) from the Indian Ocean.

A new species of the alvinocaridid shrimp genus Alvinocaris Williams & Chace, 1982 is described from the Solitaire hydrothermal vent field at 2606 m depth on the Central Indian Ridge. Alvinocaris solitaire sp. nov., the first species of the genus to be recorded from the Indian Ocean, is morphologically most similar to A. lusca Williams & Chace, 1982 from the Galapagos Rift, East Pacific Rise. The new species is distinguished from A. lusca by the less produced pterygostomial angle of the carapace, the presence of small teeth on the posterolateral margin of the third pleuron, and the lack of short plumose setae on the posteromedian margin of the telson. The genetic divergence of the mitochondrial cytochrome c oxidase subunit I (COI) gene (600 bp) among the nine Alvinocaris species analyzed clearly indicates that the new taxon is distinct from the congeneric species for which genetic data are available.