Cyclocoelum obscurum Leidy 1887

C. obscurum (Leidy, 1887)

Type host. “Jew-fish”, Megalops thrissoides Valenciennes (non Bloch & Schneider; missapplied name) (Syn. Megalops atlanticus Valenciennes) (Elopiformes: Megalopidae). Originally reported from a jew-fish; however, Stiles & Hassell (1894) suggested the actual species of fish was Stereolepis sp. (sea bass). The only fish that we could find that has been reported from the coastal waters of the USA where the general designation of “Jewfish” has been applied was the Atlantic goliath grouper, Epinephelus itajara (Lichtenstein) (Perciformes: Serranidae) (see Froese & Pauly 2014). This type host report is likely in error, as species of cyclocoelids are to our knowledge typically found in the air sacs, lungs, and infraorbital and nasal sinuses of birds and not in the stomachs of fishes.

Type location. USA, specific type locality unknown; specimen from the Comparative Anatomy Series No. 1035 at the Army Medical Museum.

Additional hosts. This species subsequently has been reported from a variety of charadriiform birds including the western sandpiper, Calidris mauri (Cabanis) (Syn. Ereunetes mauri Cabanis) (Charadriiformes: Scolopacidae); willet, Tringa semipalmata (Gmelin) (Syns. Catoptrophorus semipalmatus [Gmelin]); Symphaemia semipalmata (Gmelin) (Charadriiformes: Scolopacidae); common redshank, Tringa totanus (Linnaeus) (Syn. Totanus eurhinus Oberholaer) (Charadriiformes: Scolopacidae); common snipe, Gallinago gallinago (Linnaeus) (Syn. Capella gallinago Linnaeus) (Charadriiformes: Scolopacidae); gray-headed lapwing, Vanellus cinereus (Blyth). (Syn. Microsarcops cinereus [Blyth]) (Charadriiformes: Charadriidae); pintailed snipe, Gallinago stenura (Bonaparte) (Syn. Capella stenura [Bonaparte]) (Charadriiformes: Scolopacidae); little ringed plover, Charadrius dubius Scopoli (Charadriiformes: Charadriidae)— Yamaguti (1971). NHMUK on-line Host-Parasite Database lists 27 avian host species.

Additional localities. Reported to be basically cosmopolitan (Asia; Europe; North America)— Yamaguti (1971). NHMUK on-line Host-Parasite Database lists 15 additional localities and 37 references for this parasite species.

Previously proposed synonyms. Cyclocoelum (Cyclocoelum) obscurum (Leidy, 1887) — Bashkirova (1950); Cyclocoelum halcyonis MacCallum, 1921, Cyclocoelum problematicum (Stossich, 1902) (= Selfcoelum problematicum [Stossich, 1902] n. comb.)— Joyeux & Baer (1927); Cyclocoelum ovopunctatum Stossich, 1902 (= Selfcoelum ovopunctatum [Stossich, 1902] n. comb.), Haematotrephus fasciatus (Stossich, 1902), Cyclocoelum vicarium (Arnsdorff, 1908) (= Selfcoelum vicarium [Arnsdorff, 1908] n. comb.), Cyclocoelum leidyi, Harrah, 1922, Haematoprimum fasciatus (Stossich, 1902) (= Haematotrephus fasciatus [Stossich, 1902])— Joyeux & Baer (1927); Cyclocoelum sp. of Looss (1899), Cyclocoelum problematicum (Stossich, 1902) (= Selfcoelum problematicum [Stossich, 1902] n. comb.), Cyclocoelum exile Stossich 1902, Cyclocoelum obliquum Harrah, 1921, Cyclocoelum leidyi Harrah, 1922, Cyclocoelum cuneatum Harrah, 1922, Cyclocoelum macrorchis Harrah, 1922, Cyclocoelum toratsugumi Morishita, 1924, Cyclocoelum orientale Skrjabin, 1913, Cyclocoelum orientale eurhinus Tubangui, 1932, Cyclocoelum makii Yamaguti, 1933, Cyclocoelum capellum Khan, 1935 (= Selfcoelum capellum [Khan, 1935] n. comb.), Cyclocoelum allahabadi Khan, 1935 (= Selfcoelum allahabadi [Khan, 1935] n. comb.), Cyclocoelum indicum Khan, 1935 (= Selfcoelum indicum [Khan, 1935] n. comb.), Cyclocoelum erythropis Khan, 1935 (= Selfcoelum erythropis [Khan, 1935] n. comb.), Cyclocoelum mehrii Khan, 1935 (= Selfcoelum mehrii [Khan, 1935] n. comb.), Cyclocoelum lobatum Khan, 1935; Cyclocoelum mutabile (Zeder, 1800) — Dubois (1959).

Remarks. This species was originally erected as Monostomum obscurum Leidy, 1887. Although not adequately described by Leidy (1887), this species was redescribed by Harrah (1922) from the original material deposited at the Army Medical Museum No. 1035. Cyclocoelum obscurum is similar to C. pseudomicrostomum Harrah, 1922, but differs from this species by having a somewhat shorter cirrus sac (248–579; 4–5% of body length compared to 1,325; 9%) and larger eggs (138–162 by 70–94 compared to 102 by 51–66). This species has a rudimentary oral sucker (“weakly developed sucking musculature which measures 115Μ in diameter”)— Harrah (1922).