Examination of specimens collected from water shrews Neomys fodiens in the Rhodope Mountains, Bulgaria, revealed a new species of Soricinia. Soricinia genovi n. sp., is described and the syntype of Soricinia globosa (the only other Soricinia species known from Neomys) is redescribed. The new species differs from S. globosa in the number of proglottids, relative length of the cirrus-sac, number of eggs in gravid proglottids, absence of vaginal sphincter and other characters. Among Soricinia, parasitic in shrews of the genus Sorex, the new species is most similar to Soricinia quarta. Soricinia genovi can be distinguished from S. quarta by the length of the cirrus-sac, larger testes and ovary, position of vitellarium and armament of cirrus. Comparison of nuclear ribosomal 28S DNA sequences and mitochondrial nad1 sequences clearly distinguishes S. genovi sp. n. from S. quarta, Soricinia bargusinica and Soricinia infirma. The levels of interspecific sequence divergence among Soricinia species exceed those reported for some other hymenolepidids of mammals. Phylogenetic analysis places S. quarta and S. genovi sp. n. as the closest taxa which is in agreement with morphological evidence. Our data suggest that the specimens of Soricinia from the Altai Mountains that were morphologically closest to S. infirma represent a new species. Pairwise sequence comparisons and phylogenetic analysis also indicate that "S. infirma" group may constitute a genus separate from the remaining Soricinia.