S. vicarium (Arnsdorff, 1908) n. comb.

Type host. Purple sandpiper, Calidris maritima Brünnich (Syn. Arquatella maritime [Gmelin]) ( Charadriiformes: Scolopacidae).

Type locality. Labrador, Canada.

Additional hosts. Eurasian curlew, Numenius arquata (Linnaeus) and dunlin, Calidris alpina (Linnaeus) (Syn. Tringa alpina Linnaeus) ( Charadriiformes: Scolopacidae)— Yamaguti (1971); common greenshank, Tringa nebularia (Gunnerus) ( Charadriiformes: Scolopacidae)— Bourgat et al. (1999).

Additional localities. Europe, specific locality unknown—Yamaguti (1971); Togolese Republic (Togo), Africa—Bourgat et al. (1999).

Previously proposed synonym. Cyclocoelum mehrii Khan, 1935 (= Selfcoelum mehrii [Khan, 1935] n. comb.)— Bashkirova (1950); Dubois (1959).

Remarks. This species was originally described as Monostomum vicarium Arnsdorff, 1908 . It was redescribed as Cyclocoelum vicarium (Arnsdorff, 1908) by Harrah (1922). It was considered a synonym of Cyclocoelum ovopunctatum Stossich, 1902 (= Selfcoelum ovopunctatum [Stossich, 1902] n. comb.) by Bashkirova (1950) and Dubois (1959), and of Cyclocoelum obscurum (Leidy, 1887) by Joyeux & Baer (1927). The original description of this species by Arnsdorff (1908) apparently was based on two separate species representing different genera in two separate subfamilies. Figure 1 of the original description likely represents Selfcoelum vicarium n. comb. (Syn. Monostomum vicarium) because it has an intertesticular ovary forming a triangle with the testes (Cyclocoelinae), a genital pore that is postpharyngeal and the vitelline fields are not confluent posteriorly (= Selfcoelum). The second possible species, as shown in Fig. 2, appears to have a pretesticular ovary forming a triangle with the testes (Haematotrephinae), a genital pore that is postpharyngeal, vitelline fields that are not confluent posteriorly and the testes are oblique, and it would likely be assigned to Haematotrephus . However, with the lack of information concerning this second species, we have not distinguished it as a distinct species and have not included it in our key to the species of Haematotrephus . No oral or ventral sucker described—Arnsdorff (1908); Kossack (1911) and Bashkirova (1950).