Cyclocoelum robustum, Stossich, 1902

Dronen, Norman O. & Blend, Charles K., 2015, Updated keys to the genera in the subfamilies of Cyclocoelidae Stossich, 1902, including a reconsideration of species assignments, species keys and the proposal of a new genus in Szidatitreminae Dronen, 2007, Zootaxa 4053 (1), pp. 1-100 : 17

C. robustum Stossich, 1902

Type host. Tufted duck, Aythya fuligula (Linnaeus) (Syn. Fuligula cristata Linnaeus) ( Anseriformes : Anatidae ).

Type locality. Europe; specific type locality unknown.

Additional hosts. Species of Aythya Boie (Syn. Fuligula [Linnaeus]); tufted pochard, Nyroca fuligula (Linné) (Syn. A. fuligula ); graylag goose, Anser anser (Linnaeus) ( Anseriformes : Anatidae ) — Yamaguti ( 1971).

Additional locality. Republic of Kazakhstan; Siberia, specific localities unknown — Yamaguti ( 1971).

Previously proposed synonyms. Hyptiasmus magnus Johnston, 1917 (= Prohyptiasmus magnus [ Johnston, 1917])— Bashkirova ( 1950); Prohyptiasmus robustum ( Stossich, 1902) — Feizullaev ( 1980).

Remarks. This species was originally named Cyclocoelum robustum Stossich, 1902 , but only a body length and body width was provided in the original description. It was transferred to Prohyptiasmus Witenberg, 1923 by Witenberg ( 1923) where Prohyptiasmus robustus ( Stossich, 1902) was designated as the type species for the genus, but neither an adequate redescription nor illustrations were provided—Bashkirova ( 1950); Yamaguti ( 1971). Witenberg ( 1926) provided a representative diagram of a species of Prohyptiasmus in his Table 2, which apparently was presumed to represent P. robustus (= Cyclocoelum robustum )— Yamaguti ( 1971, Fig. 1141). The diagram of Witenberg ( 1926) shows the species to have an intertesticular ovary that is in a straight line with two tandem testes (Hyptiasminae), a prepharyngeal genital pore and the vitelline fields are not confluent posteriorly, and it would be assigned to Hyptiasmus Kossack, 1911 as suggested by Kossack ( 1911). Witenberg ( 1928) placed this species in Harrahium Witenberg, 1926 , thus removing it as the type species for Prohyptiasmus and proposed a replacement genus, Stossichium Witenberg, 1928 with S. magnum ( Johnston, 1917) as the type species. However, C. robustum , as originally described by Stossich ( 1902), has an intertesticular ovary, forming a triangle with the testes ( Fig. 11 of Stossich 1902) (Cyclocoelinae), a prepharyngeal genital pore ( Fig. 12) and the vitelline fields are not confluent posteriorly ( Fig. 11), placing it in Cyclocoelum . No oral or ventral sucker described—Stossich ( 1902).