COMPARISON OF THE CARPAL CLEANING BRUSH IN 2 GENERA OF HYDROTHERMAL VENT SHRIMP (CRUSTACEA, DECAPODA, BRESILIIDAE)

Clusters of specialized serrate setae in patches called ''carpal clean ing brushes,'' or carpal-propodal brushes, are found on the distal mar gins of the chelipedal carpus in many species of caridean shrimps and other decapod crustaceans. These brushes, used to clean the antennal f lagellum, occur in some bresiliid shrimp species associated with hydro thermal vents in the Pacific and Atlantic oceans, and recently their p resence has been proposed as a distinguishing taxonomic character at t he genus level, Occurrence of such brushes in shrimp that live near hy drothermal vents is of interest because of the high number of bacteria associated with these vents, These shrimp have the potential to be he avily fouled with bacteria, whereas at the same time preliminary studi es suggest that they may depend upon these bacteria at least in part ( or possibly exclusively) for food. We employ scanning electron microsc opy to examine and describe the general morphology and location of car pal brushes on the chelipeds of all known species in two vent shrimp g enera, Rimicaris Williams and Rona and Chorocaris Martin and Hessler. The brush is well developed and clearly delimited in all known species of Chorocaris, where it consists of a triangular field of serrate set ae and a posterior blunt spine that possibly functions as a ''stop'' t o keep the antennal flagellum in place during grooming, Rimicaris exoc ulata has no recognizable carpal cleaning brush or any serrate setae o n the chelipedal carpus and thus appears derived relative to species o f Chorocaris with regard to this feature. A newly described species, R . aurantiaca, is somewhat intermediate, having no carpal brush but wit h two serrate setae and a blunt spine in the region occupied by the br ush in species of Chorocaris. Possible implications and comparisons to the genera Alvinocaris and Opapaele are discussed briefly. (C) 1998 W iley-Liss, Inc.