Bismarck Sea, Caridea, Indo-West Pacific, Kavieng Lagoon, sponge symbiosis

A very small adult specimen of symbiotic palaemonid shrimp collected from Kavieng Lagoon, N.W. New Ireland Island, Papua New Guinea, is described as a new genus and species. Due to the slender subcylindrical body, reduced rostrum, elongated eyes and distolaterally produced uropodal exopods, the new species is somewhat similar to shrimps of the endosymbiotic sponge genus Nippontonia. Both second pereiopods are lost, but the specimen is unique by its bidentate scaphocerites, an apical corona of spiniform teeth on the mandibular molar process, five posterior telson cuspidate setae from which the median and intermediate ones are long, hooked, and the broadly spoon-like dactyli of the first pereiopods chelae with marginal pectination. Based on those characters, the new genus is without parallel among all symbiotic palaemonid shrimps. Its close phylogenetic relationship to the spongobiotic genera Nippontonia, Onycocaridella, and Thaumastocaris, is also confirmed by molecular comparison.