Helobdella is a genus of leeches in the family Glossiphoniidae, the freshwater jawless leeches. They occur worldwide.[1]
It has been difficult to define species in this genus without DNA analysis. Like other leeches in this family, some Helobdella species are polymorphic, coming in different colors and patterns. On the other hand, some uniformly colored species are actually cryptic species complexes that may be divided into separate species with genetic analysis.[2]
As of 2004 there were approximately 40 described species, with species being described and reclassified continually.[3]