Genus Oesophagodontus Railliet et Henry, 1902

Synonyms: Pseudosclerostomum Quiel, 1919

General. Large Strongylinae. Mouth collar depressed with sharp ridge on peripheral edge, undivided. Posterior edge of MC anterior to edge of BC. Amphids not markedly projected through MC surface. Tip and longer stalk of submedian papillae extend through MC. Tip of submedian papillae very long, about 4 or more times as long as thick, uniform thickness. Stalk of submedian papillae broader than long, with short bilobed process. Elements of ELC markedly less numerous than ILC and about same length. Elements of ELC longer than broad, tips pointed; insertion point on tips of ILC. Numerous elements of ILC longer than broad, tips pointed; ILC elements are bent backwards at base with free ends reflected slightly anteriorly insertion point on anterior edge of BC. Line formed by insertion of elements of ILC straight. Form of posterior edge of elements of ILC straight, unadorned. Support for ELC continuous with BC, elongate, curving, thin at one end. Septum intracoronare origin on support. Medial insertion of septum intracoronare situated anterior to junction of ELC and ILC. Walls of BC concave, with thickened posterior ring. Buccal cavity funnel-shaped wider anteriorly, wider than deep. Dorsal gutter inconspicuous. Buccal teeth absent. Esophageal funnel moderately enlarged. Esophageal teeth prominent. Anterior muscular portion of esophagus about 1/4 to 1/3 of esophagus length. Excretory pore posterior to NR. Anterior deirids near middle of glandular esophagus.

Male: Dorsal ray with 6 branches; medial fissure wide, extends to base of lobe. Ventral rays shorter than laterals. Dorsal lobe shorter then lateral lobes. Externodorsal rays origin on stem of dorsal rays. Gubernaculum small, straight, ventral groove. Genital cone short, conical. Spicule tips straight or slightly curved.

Female: Vulva 2 to3, or more, tail lengths from anus. Vagina shorter than sphincter. Ovejector vestibule broadly Y-shaped, infundibulum about equal to sphincter. Tail conical, long, more than 2x diameter at anus.

Type species: O. robustus (Giles, 1892) Railliet et Henry, 1902

Discussion

This only species in this genus was described by Giles, 1892 as Sclerostoma robustum from horses and mules in India. Later it was moved toa new genus, Oesophagodontus, by Railliet et Henry, 1902. Oesophagotontus. robustus is a rare but cosmopilitan species. It was found by Boulenger (1916) in horses in England, by Turner (1920) in zebra in an English Zoo, by Theiler (1923) in a horse and a mule in South Africa, by Popov (1927) in horses of Russia and by other authors. Theiler (1923) noted that the species is very rare in South Africa, only 3 females were found: one in a horse and 2 in a mule. As Pseudosclerostomum securiferum it was described by Quiel, 1919 from Germany (?).

Larvae of third stage O. robustus were described by Soulsby (1965) ? They have 18 triangular intestinal cells. Recently many authors around the world reported this species in coprological examinations (Mirzayans et al., 1974; Colglazier, 1977; Ambrosi, 1981 and others).However, according Eydal (1983) 9 nematode genera were recovered from faecal samples, including Oesophagodontus robustus, which had not been found during post mortem examinations. It may mean, that this species is even more rear than seems.