Biology and taxonomy of species of Ophiopsyllus and Pseudanthessius (Copepoda) associated with brittle stars (Ophiuroidea) in Belize

Three copepod associates are reported from shallow-water ophiuroids at Beli ze, Central America. Two are cancerillid siphonostomatoids: Ophiopsyllus la tus, new species, and Ophiopsyllus reductus. The third is a pseudanthessiid poecilostomatoid, Pseudanthessius deficiens. The last species, previously known from Ophioderma cinereum, was also found on Ophioderma brevispinum. I n contrast, species of Ophiopsyllus appear be to host-specific. Ophiopsyllu s reductus is found exclusively on Ophiocoma echinata. Ophiopsyllus latus i s found only on Ophiocomella ophiactoides (with the exception of two doubtf ul records from Ophiocoma pumila). Previous records of Ophiopsyllus reductu s on Ophiocomella ophiactoides are incorrect. Comparisons between Jamaican and Belizean populations of Ophiopsyllus latus reveal similarities and diff erences and suggest that the parasitic effects of the species are minimal. On approximately 17-57% of O. ophiactoides examined there are 1-4 O. latus, which generally clasp the first or second arm joint near the edge of the d isk. They face toward the mouth of the host, possibly orienting to the curr ents emanating from the bursae or to food in the oral region. In Belize, on ly one instance of physical injury to the host was noted, although parasiti c damage has been reported in Jamaica. Furthermore, a published report that O. latus inhibits the sexual reproduction of the host appears to be unwarr anted.