Meeting Abstract

41.6  Monday, Jan. 5  Hypersymbioses in the pinnotherid crabs (Decapoda: Brachyura: Pinnotheridae): a review MCDERMOTT, J.J.; Franklin and Marshall College jmcdermo@fandm.edu

Members of the brachyuran family Pinnotheridae are nearly all symbionts of other invertebrates; some crabs are subtly parasitic and others commensalistic. Most live inside bivalve mollusks or in the tubes or burrows of polychaetes and other marine crustaceans. Animals living on or in pinnotherid crabs are considered hypersymbiotic. Hypersymbionts are poorly represented within 26 members (≈8.6%) of the Pinnotheridae (20 species in the subfamily Pinnotherinae and 6 species in the Pinnothereliinae). Parasitic hypersymbionts are as follows: 3 species of fungi; 1 unidentified cestode (Trypanorhyncha); 1 unidentified trematode (Microphallidae); nematode cysts; 3 species of Nemertea (Carcinonemertidae); 2 species of rhizocephalans (Sacculinidae; plus 5 or more unidentified species); epicaridean Isopoda (13 species of Bopyridae and 1 species of Entoniscidae, plus 3 unidentified). Preliminary biological information on unidentified entoniscids is presented. A variety of mainly incidental hypersymbioses involving ectosymbionts is known primarily from Pinnixa chaetopterana, a symbiont of polychaete burrows. The ctenostome bryozoan Triticella elongata, the only known obligate symbiont of P. chaetopterana, infests five other species of pinnotherids. Some other ectosymbionts are stalked ciliates, hydroids, polychaetes, bivalve mollusks, balanomorphan barnacles, harpacticoid copepods, and urochordates. Factors influencing our meager knowledge of hypersymbioses in the Pinnotheridae are discussed, among them the inaccessibility of crab hosts and research emphasis on taxonomy within the family