A NEW GENUS AND SPECIES OF CARIDEAN SHRIMP (CRUSTACEA, DECAPODA, BRESILIIDAE) FROM HYDROTHERMAL VENTS ON LOIHI SEAMOUNT, HAWAII

Opaepele loihi, new genus and species, is described from hydrothermal vents on Loihi Seamount, Hawaii, a mid-plate, hot-spot volcano at 18 degrees 55'N, 155 degrees 16'W, 980 m depth. This new form is related to several other bresiliid shrimps associated with hydrothermal vents, brine and hydrocarbon seeps. It has a laterally broadened triangular rostrum inconspicuously toothed on dorsal and ventral margins, carapace with pterygostomian spine present, and eyes reduced and fused mesially. This combination of characters places it in an intermediate position between a group of species in the genus Alvinocaris Williams & Chace with well developed compressed toothed rostrum, carapace with pterygostomian spine present, and eyes on separate movable stalks, and a group of species with rostrum absent (genus Rimicaris Williams) or much reduced (genus Chorocaris Martin & Hessler), carapace with pterygostomian spine absent, and eyestalks reduced and fused mesially. Only two of the vent/seep bresiliid species are now known from depths less than 1000 m, A. stactophila Williams, from hydrocarbon seeps at 5 34 m in the Gulf of Mexico, and the present new species at 980 m.