Cestode Diversity of Shrews on the Kamchatka Peninsula and Paramushir Island

Abstract

The aim of this study was to assess the taxonomic diversity and prevalence of shrew cestodes on the Kamchatka Peninsula and Paramushir Island on the basis of current understanding of cestode taxonomy. The diversity of shrew cestodes included 22 species from three families: Hymenolepididae, Dilepididae, and Mesocestoididae. In Paramushir, the diversity of shrew cestodes was substantially lower than in Kamchatka (14 and 22, respectively). In Kamchatka, three genera of cestodes (Novobrachylepis, Mathevolepis, Ditestolepis) were not found, but three species from genera Lineolepis, Staphylocystis, and Monocercus are possibly new species. The potential for endemic species and the unique characteristics of the cestode fauna on Kamchatka suggest that the peninsula may have been a refugium for shrews and their parasites in the last glacial maximum. In Kamchatka and Paramushir, two Nearctic species (Lineolepis parva and L. pribilofensis) were found, which indicates potential dispersal from North America. Most cestode species in Kamchatka were associated with the host shrew Sorex caecutiens, while in Paramushir most cestodes were associated with Sorex isodon. In Paramushir, shrews had higher prevalence of infection with cestodes than in Kamchatka. The dominant cestode taxa in shrews on Paramushir Island were species rare in Kamchatka. Conversely, the most abundant cestode species in shrews on Kamchatka were absent from the island fauna.