PARASITIC CASTRATION OF THE CRAB, TUMIDOCARCINUS-GIGANTEUS GLAESSNER,FROM THE MIOCENE OF NEW-ZEALAND - COEVOLUTION WITHIN THE CRUSTACEA

Feminization of adult male xanthid crabs, Tumidocarcinus giganteus Gla essner, from the Miocene of New Zealand, represents the first notice o f the phenomenon in the fossil record. Marked broadening of the abdome n of adult males, to assume a form much like that of mature females an d limitation in the size of the major claw likely result from parasiti c castration by rhizocephalan, probably kentrogonid, barnacles. A sexu ally aberrant dakoticancrid, Dakoticancer overanus Rathbun, from the L ate Cretaceous of South Dakota (Bishop, 1983) may extend this coevolut ionary relationship between parasitic barnacles and decapod crustacean s into the Mesozoic.