Paragymnophallus odhneri gen. n., sp. n. (Trematoda: Gymnophallidae) for Gymnophallus somateriae sensu Odhner (1900, 1905)

Abstract

Odhner's specimens of Gymnophallus somateriae were studied and are assigned to a new genus and new species because of the wide genital pore located between the ventral sucker and the intestinal bifurcation. Paragymnophallus odhneri also differs from G. somateriae as described by Levinsen (1881) and Ching (1973), in the body spination, 2:1 sucker ratio, nature of the vitellaria, and the egg size. G. somateriae reported by Ryzhikov et al. (1966) from Somateria spectabilis in Chutkova is considered to be P. odhneri because of the checkerboard arrangement of spines, 2:1 sucker ratio, and small eggs. Pending reexamination of the genital pore, G. bilis Brinkmann, 1956 and G. minor Ryzhikov, 1962 could belong to Paragymnophallus. The new genus, most similar to Gymnophallus in the bipartite seminal vesicle, follicular vitelline glands, and Y-shaped excretory bladder, differs in the location and size of the genital pore, larger sucker ratio, and large pharynx. The wide genital pore some distance from the ventral sucker and the large oral sucker are like that of Parvatrema but Parvatrema has a club-shaped seminal vesicle, minute body, compact vitellaria, and V-shaped excretory bladder. A key to the genera of Gymnophallidae is included.