[Monocercus dokuchaevi sp. n. (Cyclophyllidea: Dilepididae)--a new species of cestodes from shrews of the North-Eastern Asia].

A new cestode species, Monocercus dokuchaevi sp. n. is described from shrews of the genus Sorex from the Middle Kolyma plateau (Magadan Province). The new species is most closer to M. soricis (Neiland, 1953) by having regular alteration of genital atriums in the short strobila (up to 10 mm only). The size of rostellar hooks in M. dokuchaevi is intermedial between those in M. soricis and M. arioni (Sibold, 1850). In Monocercus dokuchaevi, the length of rostellar hooks is 0.038-0.045 mm (average 0.045 mm), in M. arioni, average is 0.05 mm, in M. soricis, limits are 0.027-0.033 mm. Two other species of the genus, M. baicalensis Eltyshev, 1971 and M. estavarensis Euzet et Jourdan, 1968, have much longer rostellar hooks, 0.07-0.08 and 0.092-0.106 mm, respectively, whereas the genital atriums in these species are altered irregularly.