Genus Tridentoinfundibulum
Tshoijo, in Popova, 1958

General. Middle-sized Cyathostominae. MC flattened, divided into inner and outer rings. Posterior edge of MC posterior 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 bulbous, 2 times long as thick. Stalk of submedian papillae broader than long. Elements of ELC longer than broad, tips pointed; insertion point on tips of ILC. Elements of ILC difficult to distinguish, slightly longer than broad, identical in number to ELC; insertion point at 1/4 or less of BC depth. 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 anteriorly to junction of ELC and ILC. Walls of BC straight, thicker in middle. Buccal cavity wider than deep, cylindrical. Dorsal gutter short, broad at base, less than 1/2 of BC depth. Buccal teeth absent. Esophageal funnel enlarged, especially in dorsal sector which forms invagination containing 3 esophageal teeth . 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. Ventral rays shorter than laterals. Dorsal lobe longer then lateral lobes. Externodorsal rays origin at junction of dorsal and laterals rays. Gubernaculum large, with dorsal handle and ventral notch. Genital cone short, conical. Spicule tips hook- or harpoon-shaped

Female: Vulva more than 1 tail length from anus. Vagina shorter than sphincter of ovejector. Ovejector vestibule oval or Y-shaped, infundibulum longer than sphincter. Tail conical, short, length less than 2x diameter at anus.

Type species: T. gobi Tshoijo in Popova, 1958

Discussion

Although much remains to be learned about the generic relationships of this species, only recently described in enough detail to be recognized (Dvojnos and Kharchenko, 1994). this is a good species that has been collected in Asia, North America and Europe (Lichtenfels et al., 1998). Lichtenfels and Klei (1988) described this species as Cylicostephanus torbertiae. Tridentoinfundibullum is recognized at genus level here because it appears on the basis of morphological (Lichtenfels and Hoberg, unpublished) and molecular phylogenies (McDonnell et al., 2000; Hung et al. 2000) to be within a clade that includes Cylicostephanus and closer to, but separated from, Cylicodontophorus. Hartwich (1986) did not study this species.