Class Aphanoneura

The Aphanoneura are a class of Annelida, with an equivocal relationship with clitellates (oligochaetes and leeches) and no clear affiliation with any of the traditional polychaete groups (Struck & Purschke, 2005; Zrzavy´ et al., 2009). They comprise two families, Aeolosomatidae and Potamodrilidae, which have been included among the Polychaeta in previous reviews of freshwater annelids (Glasby & Timm, 2008; Glasby et al., 2009). Aeolosomatidae, currently considered Annelida incertae sedis (WoRMS, 2012), is the most diverse and abundant aphanoneuran represented in the Palaearctic by three genera: Rheomorpha Ruttner-Kolisko, 1955 (one species), Hystricosoma Michaelsen, 1926 (one species) and Aeolosoma Ehrenberg, 1828 (at least 20 species). The Potamodrilidae is represented in the Palaearctic by a single species, Potamodrilus fluviatilis (Lasto ckin, 1935.)