Cylicostephanus asymetricus (Theiler, 1923)
Ihle, 1925 Cram, 1925

Figures

Synonyms: Cylicostomum asymetricum Theiler, 1923; Cylicotetrapedon asymetricum (Theiler, 1923) Ihle, 1925; Schulzitrichonema asymetricum (Theiler, 1923) Ershov, 1943; Erschowinema asymetricum (Theiler, 1923) Tshoijo, 1957

General: Tip of submedian papillae bulbous, less than 2times as long as thick. ELC with 15 elements; ILC with 26. Insertion for ELC on tips of elements of ILC. ILC elements broad, with rounded tips; in palisade. Insertion for ILC at 1/4 or less of BC depth. Septum intracoronare origin placed on BC. Walls of BC concave; thicker anteriorly. Buccal cavity wider than deep. Dorsal gutter elongate, more than 1/2 depth of BC. Anterior deirids and excretory pore 440-500 from anterior end.

Male: Body length 7.5-8.0 mm. Esophagus length 440-500. BC width 50-60; depth 18-020 dorsally and 24 ventrally. Spicule length 1.0-1.1 mm. Gubernaculum with large handle, ventral notch inconspicuous; length 156-161. Dorsal ray length 380. Ventral rays length equal to laterals. Dermal collar well-developed on ventral side of genital cone. Appendages of genital cone paired, plates fused medially with numerous, long, sharp projections. Protrusions of dermal collar absent.

Female: Body length 7.5-8.0 mm. Esophagus length 380-451. BC width 40-68; depth 20-29. Vagina length 0.400-0.480. Anus to tail tip 120. Egg size 90-100 x 40-48. Infundibulum length about equal to sphincter length. Tail of mature female digitiform, straight, tip pointed; sublateral protrusions undeveloped.

Hosts: Equus caballus, E. asinus

Locality: cecum, colon.

Distribution: cosmopolitan.

Discussion: Hartwich (1986) pointed out that Trichonema parvibursatum Vaz, 1934, which was described with a short dorsal gutter, is more likely a synonym of C. goldi than C. hybridus. We follow Hartwich (1986) in considering Cylicostephanus ornatus (Kotlan, 1919) to be a synonym of C. goldi.