A new genus and species of copepod crustacean, Nannallecto fusii, is recorded parasitic on the pteropod, Pneumodermopsis (Pneumodermopsis) paucidens (Boas, 1886), from a surface tow off French Guiana. The parasite is obviously related to the only other adult copepod associate known from pteropods, the recently discovered Micrallecto uncinata Stock, 1971, and it appears to belong likewise to the family Splanchnotrophidae. The present new genus differs chiefly from Micrallecto in the presence of strong maxillipeds.