The systematics of the 37-collar spined echinostomes within the revolutum group has long been confused because of both the morphological similarity between members of the group and the inadequate or poor specific diagnosis (or both) of several newly established taxa. Furthermore, the absence or loss of type-material for several species further complicated the situation. As a result, this group has been characterized by a long history of synonymies and inadequate specific diagnosis (see Kostadinova and Gibson, 2000 for review).
Kanev and coworkers (see Kanev, 1994; Kanev, Dimitrov et al., 1995; Kanev, Fried et al., 1995 and references therein) in 1994–1995 attempted to clarify the systematics of this group and concluded that species-specific characteristics in the revolutum group are only expressed in their larval stages, in their host–parasite relationships, and their geographical distribution on a continental scale. They considered only 5 species as valid within the revolutum group: Echinostoma...