Genus Skrjabinodentus Tshoijo, in Popova, 1958

General. Small-sized Cyathostominea. MC flattened, divided into inner and outer rings. Posterior edge of MC posterior to anterior edge of BC. Amphids not markedly projected through MC surface. Tip and longer stalk of submedian papillae extend through MC. Tip of submedian papillae spindle-shaped, 2 - 3 times or more as long as thick. Stalk of submedian papillae broader than long. ELC and ILC elements of similar length; ELC elements markedly less numerous or nearly equal in number to ILC. Elements of ELC longer than broad or as long as broad, tips pointed; insertion point on tips of ILC. Elements of ILC as long as broad or broader than long, tips pointed or rounded; 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, short, triangular in optical section. Septum intracoronare origin on support. Medial insertion of septum intracoronare situated anteriorly to junction of ELC and ILC. Walls of BC S-shaped, much thicker anteriorly. Buccal cavity wider than deep, wider posteriorly. Dorsal gutter well-developed, 1/3 to 2/3 of depth of BC. Buccal teeth absent. Esophageal funnel enlarged, lined with thick cuticle. 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 or near EI.

Male: Proximal and middle rays of dorsal ray fused. Ventral rays may have different length relative to laterals. Dorsal lobe longer then lateral lobes. Externodorsal rays origin at junction of dorsal and laterals rays. Gubernaculum large, small handle, enlarged distal tip. Genital cone elongate, extends beyond bursal edge. Spicule tips hook- or harpoon-shaped.

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

Type species: S. caragandicus (Funicova, 1939) Tshoijo in Popova,1958

Discussion

The three species in the genus Skrjabinodentus share several distinguishing characteristics: (1) the proximal and middle branches of the dorsal bursal ray are fused completely or almost to the distal tips; (2) the genital cone is greatly elongated; and, (3) the gubernaculum is modified by a reduction in size of the handle and the presence of posterior alae. Dvojnos and Kharchenko (1994) recognized Skrjabinodentus at genus level; Lichtenfels and Klei (1988) recommended the use of Skrjabinodentus at subgenus level within Cylicostephanus; and, Hartwich (1986) tentatively placed C. caragandicus in Cylicostephanus. The consensus of the 1997 Sun City Workshop (Lichtenfels et al., 1998) was to recognize this group of three similar species at genus level. Information is needed on the characteristics of the mouth collar and support for the ELC as described by Hartwich (1986) and molecular studies are lacking.