The Aquatic Oligochaeta (Aeolosomatidae, Opistocystidae, Naididae) of Central America

Twenty species of aquatic oligochaetes are reported from Costa Rica, El Salvador, Guatemala, Nicaragua, and Honduras. Species are in the families Aeolosomatidae, Opistocystidae, and Naididae. Setal measurements are cited for each species and compared with measurements from other parts of the range. Seven of the species are cosmopolitan and seven show neotropical affinities, while only two show nearctic relationships. Two species, Pristina menoni and Dero plumosa, are reported for the first time from the Western Hemisphere. The Central American republics have very few recorded species of aquatic oligochaetes, although some of the terrestrial species have been studied. Over a decade has been spent in gathering these few collections, and since no additional effort is anticipated in the near future, it is deemed appropriate to publish these records.