Comparative Functional Morphology of Mouthparts and Associated Structures of Kalliapseudes Sp. A McSweeny, 1968, and Psammokalliapseudes granulosus Brum, 1973 (Crustacea: Tanaidacea), with a Description of the Male of Psammokalliapseudes granulosus

The feeding mechanism of two species of the tanaidacean family Kalliapseudidae: Kalliapseudes sp. A McSweeny 1968, and Psammokalliapseudes granulosus Brum 1973, was elucidated by comparing gut contents, mouthpart morphology, and feeding behavior. This was achieved by using a combination of light microscopy, scanning electron microscopy, and observation of living organisms. Morphological differences of the mouthparts are directly associated with the feeding mechanism. Kalliapseudes sp. A filter feeds and possesses plumose setae on the chelipeds, maxillipeds, and maxillae. When building their tubes, P. granulosus scrapes detritus off sand grains by using the comb setae on the maxillae. They suspension feed when settled in their tubes by trapping detritus on the antennular setae. Both species feed primarily on detritus. Diatoms were the second most abundant food item in the foregut of Kalliapseudes sp. A. Comparisons of foregut morphology were made that attempted to relate structure and function. Foreguts were nearly identical, which could be attributed to the utilization of a common food source. The male of P. granulosus is described and illustrated for the first time. Two forms of copulatory males differ with respect to cheliped shape and pereopod setation.