New Shrimps (families Procarididae and Atyidae) from a Submerged Lava Tube on Hawaii

A new genus and species of procaridid shrimp, Vetericaris chaceorum, and a new atyid species, Halocaridina palahemo, are described from the island of Hawaii. The new genus, regarded as more primitive than Procaris, is characterized by the possession of a larger number of gills than Procaris, including arthrobranchs and pleurobranchs on the third maxilliped and pereiopods 1-4, elongate pleopodal endopods, appendices internae on pleopods 3-5, and elongate dactyls on pereiopods 1-5. Reexamination of the two genera of procaridids would seem to indicate a greater affinity with the caridean shrimps than with the dendrobranchiate shrimps. The new Halocaridina differs from its only congener in several features, including a shorter rostrum, a more inflated carapace, and less inflated chelae. Reference to Pleistocene geological history, and present-day hydrological conditions strengthen the argument for relatively deep anchialine refugia from which dispersal took place, to explain the distribution of anchialine shrimps. During a 1985 survey of anchialine and marine caves of the Pacific by Dr. Thomas M. Iliffe and the second author, several sites in the Hawaiian archipelago were investigated by diving with SCUBA. In the course of working in the cave called Lua o Palahemo on Hawaii Island, several crustaceans, including shrimps, isopods, and copepods were collected. These were passed on to the first author for evaluation. The discovery of an undescribed procaridid and atyid shrimp in this material revealed further problems in the relationships of the major taxa of decapod shrimps. These problems are explored in the present paper.