Ripistes parasita (Schmidt) (Oligochaeta:Naididae), a Distinctive Oligochaete New to North America

Abstract

Ripistes is a monospecific genus (containing only R. parasita (Schmidt)) easily distinguished from other naidid worms by the bundles of extremely long capilliform chaetae on body segments VI-VIII. Its occurrence in New York State is the first record of the genus outside the Palearctic region. In general, the New York specimens conformed to the morphological traits of the Palearctic material, but none were more than half as long as the known maximum length, some dorsal and ventral chaetae were somewhat shorter, and the penial chaetae were occasionally more numerous and always considerably longer. The New York specimens were collected from hardboard artificial substrate samplers, usually with several other species of naidids. The use of artificial substrates may have been instrumental in finding the species, since it is known to live on the surfaces of submerged objects, rather than on the benthic substrate per se.