Hyptiasmus arcuatus

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 : 60

Hyptiasmus arcuatus ( Brandes, 1892 of Stossich, 1902)— Type species

Syn. H. coelonodus Witenberg, 1923

Type host. Probably the ferruginous duck, Aythya nyroca (Güldenstädt) (Syn. Nyroca clangula [Linnaeus], but Nyroca Fleming is now a synonym of Aythya Boie ) ( Anseriformes : Anatidae ).

Type locality. Germany; specific type locality unknown.

Additional hosts. Smew, Mergellus albellus (Linnaeus) ( Anseriformes : Anatidae )— Yamaguti (1934); species of Anas Linnaeus , Anser Brisson , Bucephala Baird (Syn. Glaucionetta Stejneger ), Clangula Leach, Fulica Linnaeus , Melanitta Boie (Syn. Oidemia Fleming), Somateria Leach and Turdus Linnaeus—Yamaguti (1971) ; common or red-headed pochard, Aythya ferina (Linnaeus) (Syn. Fuligula ferina Linnaeus) ( Anseriformes : Anatidae )— Witenberg (1923). NHMUK on-line Host-Parasite Database lists 13 avian host species for H. arcuatus and the red-head pochard or red-headed duck, Fuligula ferina (Linnaeus) ( Anseriformes : Anatidae ), as a host for H. coelonodus (see Chertkova et al. 1994).

Additional localities. Sizuoka Prefecture—Yamaguti (1934); Europe, Japan, Salvador ( Brazil) and Siberia— Yamaguit (1971). NHMUK on-line Host-Parasite Database lists 8 localities and 16 references for H. arcuatus and the “European USSR ( CIS)” as a locality for H. coelonodus (see Chertkova et al. 1994).

Previously proposed synonyms. Hyptiasmus laevigatus Kossack, 1911 , H. tumidus Kossack, 1911 , Hyptiasmus oculeus ( Kossack, 1911) , H. magnus Johnston, 1917 , H. coelonodus , Transcoelum oculeum ( Kossack, 1911) (= Hyptiasmus oculeus ), and Transcoelum sigillum Witenberg, 1923 (= Hyptiasmus sigillum [ Witenberg, 1923] n. comb.)— Joyeux & Baer (1927); Hyptiasmus laevigatus , Hyptiasmus tumidus , Hyptiasmus coelonodus , Hyptiasmus theodori Witenberg, 1928 — Dubois (1959).

Remarks. This species was originally erected without description or illustrations as Monostomum arcuatum Brandes, 1892 . Stossich (1902) considered Monostomum arcuatum to be a nomen nudum and therefore provided a minimal description with an illustration, and transferred this species to Cyclocoelum . Kossack (1911) transferred it to Hyptiasmus , and redescribed and reillustrated the species from specimens deposited in the Berlin Museum (Berliner Sammlung, No. 2586). Hyptiasmus coelonodus also was originally described from a species of Aythya (Anatidae) from Europe, and differs from H. arcuatus by having a somewhat larger intertesticular space (1,500 long, 9% of body length compared to about 700, 6%); however, these values are within the normal ranges in species of cyclocoelids and H. coelonodus otherwise cannot be distinguished from H. arcuatus ; therefore, it is placed in synonymy with H. arcuatus . No oral or ventral sucker described—Stossich (1902); Kossack (1911); Witenberg (1923, 1926); Bashkirova (1950).