A revision of the genus Orthosplanchnus Odhner, 1905 with consideration of the genera Odhneriella Skriabin, 1915 and Hadwenius Price, 1932 (Digenea: Campulidae)

Abstract

The present paper concerns digeneans of the subfamilies Odhneriellinae Yamaguti, 1958 and Orthosplanchninae Yamaguti, 1958, family Campulidae Odhner, 1926, and is based mainly on specimens collected since 1949 from marine mammals from seas bordering Alaska. Odhneriella rossica Skriabin, 1915, type species of the subfamily Odhneriellinae, is transferred to the genus Orthosplanchnus Odhner, 1905. Odhneriellinae thus becomes a synonym of Orthosplanchninae, which includes three genera: Orthosplanchnus Odhner, 1905 (syn. Odhneriella Skriabin, 1915); Hadwenius Price, 1932 (syn. Leucasiella Krotov and Deliamure, 1952); and Oschmarinella Skriabin, 1947. Seven species are retained in Orthosplanchnus: O. arcticus Odhner, 1905; O. fraterculus Odhner, 1905; Orthosplanchnus rossicus (Skriabin, 1915) n.comb. (syn. Odhneriella rossica Skriabin, 1915); O. pygmaeus Iurakhno, 1967; O. albamarinus Treshchev, 1968; O. oculatus Iurakhno, 1969; and O. antarcticus Kurochkin and Nikol'skii, 1972 (syn. O. weddelli Beverley-Burton, 1972). Orthosplanchnus elongatus Ozaki, 1935 is transferred to the genus Hadwenius, as is Odhneriella subtilus (A. S. Skriabin, 1959); O. sudarikovi Treshchev, 1966, excluded from Orthosplanchnus, is of uncertain generic allocation. Orthosplanchnus rossicus is redescribed, and descriptions are provided for the other species recognized in the genus. Variation in O. arcticus from various hosts is considered; in bearded seals, Erignathus barbatus (Erxleben), clinal variation was apparent in O. arcticus, with body size increasing from north to south.