H. sigillum (Witenberg, 1923) n. comb.

Type host. Eurasian coot, Fulica atra Linnaeus (Gruiformes: Rallidae)— Chertkova et al. (1994).

Type locality. Russian Federation (European USSR [CIS]); specific type locality unknown—Chertkova et al. (1994).

Remarks. This species was originally described as Transcoelum sigillum Witenberg, 1923 (& 1926), but was considered to be a synonym of Cyclocoelum (H.) oculeum (Kossack, 1911) (= H. oculeus Kossack, 1911) and of Cyclocoelum arcuatum (Brandes, 1892) (= H. arcuatus [Brandes, 1892 of Stossich, 1902]) by Joyeux & Baer (1927). This species was described from a specimen that was “bad and therefore it is not possible to see all details of its morphology” (Witenberg 1923). As originally described the intertesticular ovary is nearly in a straight line with the testes (Hyptiasminae), the genital pore is prepharyngeal (above mid-level of pharynx), and the vitelline fields are confluent posteriorly. No oral or ventral sucker present—Witenberg (1923).