Redescription and taxonomic position of Rodentolepis ( sensu lato ) asymmetrica (Janicki, 1904), with the erection of Kontrimavichusia n. g. (Eucestoda: Hymenolepididae) from arvicoline rodents (Rodentia: Cricetidae).

Rodentolepis ( sensu lato ) asymmetrica (Janicki, 1904) is redescribed on the basis of materials from Microtus agrestis , Microtus arvalis and Myodes glareolus from Eastern Europe (Belarus, Lithuania, Latvia, Estonia, Ukraine and the north-eastern part of Russia). A new genus, Kontrimavichusia n. g., is proposed for it based on morphological and molecular evidence. The unique morphological diagnostic characters of this currently monotypic genus include the presence of an armature on the suckers, ventral osmoregulatory canals connected with irregularly spaced transverse anastomoses, an internal seminal vesicle with circular musculature and uterus with numerous diverticula, situated dorsally to the genital ducts, extending bilaterally beyond the longitudinal osmoregulatory canals. In addition, the new genus differs from morphologically related genera of the Rodentolepis clade by the structure of its vagina. The copulatory part of the vagina in specimens of Kontrimavichusia n. g. is surrounded by circular musculature and covered externally by a dense layer of intensely-stained cells; the conductive part of the vagina is clearly distinguishable from the seminal receptacle. Molecular analysis of the partial 28S rRNA gene fully supports the erection of Kontrimavichusia n. g. as a distinct lineage.