Re-evaluation of the species composition of Bashkirovitrema Skrjabin, 1944 (Digenea: Echinostomatidae), with the description of two new species of this genus and the proposal of Kostadinovatrema novaeguiniense n. g., n. sp.

A comparison of specimens previously identified as Bashkirovitrema incrassatum (Diesing, 1850) from the African or cape clawless otter Aonyx capensis, and the speckle-throated or spotted-throated otter Hydrictis maculicollis from the Old World with specimens and descriptions of B. incrassatum from the New World showed that those from Africa (Bashkirovitrema africanum n. sp.) had a more extensive distribution of the vitelline fields than either B. canadense n. sp. from the northern river otter Lontra canadensis and the American mink Neovison vison (North America) and B. incrassatum from the Neotropical river otter Lontra longicaudis (South America). B. africanum n. sp. further differs from B. canadense n. sp. by having a smaller body, shorter forebody, smaller oral sucker, longer cirrus, shorter intertesticular space, shorter post-testicular space and longer eggs. B. canadense n. sp. can be distinguished from B. incrassatum by having a longer body, longer forebody, smaller sucker ratio, smaller testes, greater distance between the ventral sucker and the ovary, shorter cirrus-sac, longer post-testicular space and narrower eggs. B. africanum n. sp. differs from B. incrassatum by having a smaller ventral sucker, larger ovary, shorter cirrus-sac, smaller intertesticular space, larger post-testicular space and longer eggs that are not as wide. Kostadinovatrema n. g., as represented by K. novaeguiniense n. sp., can be separated from species of Bashkirovitrema Skrjabin, 1944 by having a wider body width to length profile, a head collar that is narrower than the forebody and armed with 33 rather than 27 collar spines, an ovary that is further removed anteriorly from the testes, and a dorso-ventrally flattened hindbody that is nearly as broad as the forebody. The new genus differs from Hypoderaeum Dietz, 1909 and Moliniella Hübner, 1939 by having 33 head collar spines.