Genus Craterostomum Boulenger, 1920

General. Small Strongylinae. 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 bullet-shaped, round or oval, short. Stalk of submedian papillae longer than broad. Number of elements of ELC less numerous and longer than elements of ILC.. Elements of ELC as long as broad, tips pointed ; insertion point on tips of ILC. Elements of ILC as broad as long, tips pointed; 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 surrounds anterior edge of BC, short, triangular in optical section. Septum intracoronare origin on support. Medial insertion of septum intracoronare situated at junction of ELC and ILC. Walls of BC concave, thicker anteriorly. Buccal cavity wider posteriorly, wider than deep. Dorsal gutter elongate, more than 1/2 depth of BC. 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. Ventral rays shorter than laterals. Dorsal lobe longer then lateral lobes. Externodorsal rays origin on stem of dorsal rays. Gubernaculum with small handle, enlaged distal tip. Genital cone short, conical. Spicule tips straight or slightly curved.

Female: Vulva more than 1 tail length from anus. Vagina shorter than sphincter. Ovejector vestibule oval or Y-shaped, infundibulum about equal to sphincter. Tail conical, long, more than 2x diameter at anus.

Type species: C. acuticaudatum (Kotlan, 1919) Ihle, 1920

Species inquirenda: Craterostomum tenuicauda Boulenger, 1920; Craterostomum tenuicauda, of Rai, 1960.

Discussion

Lichtenfels (1975) reviewed the history of this genus and the 3 species proposed. He agreed with Skrjabin and Ershov (1933) and most subsequent workers that C. mucronatum is a synonym of C. acuticaudatum. However, the status of C. tenuicauda is not so clear. The original description of C. tenuicauda was of females only and they were immature. Most workers (Popova, 1955) subsequently regarded this species to be a synonym of C. acuticaudatum. However, Rai (1960) redescribed C. tenuicauda from mature females and males from a pony collected in India, separating it from C. acuticaudatum on the basis of a different number of ILC and ELC elements (18 and 9, compared with 22-26 and 6-8 in C. acuticaudatum}, a proportionately shorter tail although the body length is greater, and the presence of submedian cephalic papillae that are not notched. Rai’s description of the female tail and his drawing of it do not agree with each other and are thus questionable. Neither the tail of Rai's females nor the unnotched character of the submedian papillae agree with the Boulenger’s (1920) description of C. tenuicauda or with the generic diagnosis of Craterostomum. The status of C. tenuicauda, of Boulenger, 1920 and of C. tenuicauda, of Rai, 1960, which are unlikely to be conspecific based on differences in the morphology of the females, are uncertain and need further study. We consider C. tenuicauda Boulenger, 1920 to be a species inquirenda. Rai’s (1960) specimens should not be considered to be C. tenuicauda. They may represent an undescribed species, but discrepancies in the description prevent consideration of its status until specimens can be studied.