Clitellate evolution and leech diversity: Glossiphoniidae excl. Helobdella (Annelida: Hirudinea: Rhynchobdellida) from South America

Abstract

A review of the valid species of Glossiphoniidae other than Helobdella produced 25 nominal species reported to date from South America. These species belong to the following taxa: Glossiphoniinae: Placobdella (4 species); Haementeriinae: Alboglossiphonia (1 species); Haementeria (16 species); Maiabdella (1 species); Trybothrynobdella (1 species); Theromyzinae (bird leeches): Theromyzon (2 species). 88% of this fauna is endemic to the South American continent. Full synonyms and detailed South American occurrences are provided. This is the fi rst reassessment of these South American glossiphoniid leeches in 26 years. I also provide a history of ideas on clitellate phylogeny, and summarize recent results on leech evolution. Although molecular phylogenies consistently fail to indicate the sister group of the Euclitellata, the interstitial estuarine worms belonging to the Questidae share several synapomorphies with true clitellates: direct development, bifi d and hair chaetae, a cocoon producing clitellum and sperm stored in spermathecae in females, as well as gonads limited to a few segments in both sexes. From an applied perspective, I suggest the use of leeches in ecological studies of environmental impact, given their unprecedented rates of endemicity among freshwater organisms.