Genus Parapoteriostomum Hartwich, 1986

General. Medium-sized to large Cyathostominea.. MC large and arched, undivided. Posterior edge of MC anterior or 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-shapedor round, short. Stalk of submedian papillae broader than long or longer than broad. Elements of ELC markedly more numerous and shorter than elements of ILC. Elements of ELC longer than broad, tips pointed; insertion point on tips of ILC. Elements of ILC longer than broad, tips pointed; insertion point at 1/4 or of BC depth or deeper. Line formed by insertion of elements of ILC deeper in BC dorsally and ventrally than laterally. 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 at junction of ELC and ILC. Walls of BC straight in lateral view, or slightly convex in dorsoventral view, thicker anteriorly or posteriorly, with distinct notch at posterior edge. Buccal cavity wider than deep, wider posteriorly. Dorsal gutter button-like or absent. Buccal teeth absent. Esophageal funnel enlarged. Esophageal teeth not prominent. Anterior muscular portion of esophagus about 1/4 to 1/3 of esophagus length. Excretory pore posterior to NR. Anterior deirids near EI.

Male: Dorsal ray with 6 branches. Ventral rays longer than laterals. Dorsal lobe longer then lateral lobes. Externodorsal rays origin on stem of dorsal ray or at junction of dorsal and laterals. Gubernaculum simple, without manubrium, and groove-like with paired ventral prominences. Genital cone sometime conspicuously long, extends beyond bursal edge. Spicule tips hook- or harpoon-shaped.

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

Type species: P. mettami (Leiper,1913) Hartwich, 1986.

Discussion

Hartwich (1986) erected Parapoteriostomum for three species formerly in the genus Cylicodontophorus, which shared with Poteriostomum these and other characteristics, a mouth collar not divided into 2 rings, septum intracoronare extending from the middle of the support to the junction of the leaf-crowns, elements of ELC fewer and shorter than ILC We add here P. mongolicia described originally in the genus Cylicodontophorus, and redescribed by Dvojnos and Kharchenko (1988). The independence of Parapoteriostomum and its relationship to Poteriostomum recognized by Hartwich (1986) are strongly supported by the molecular data of Hung et al. (2000)and the preliminary morphological phylogeny by Lichtenfels et al. (unpublished). Based on the English abstract of the description of Cylicodontophorus zhongweiensis Li and Li, 1993, it was synonomized (Lichtenfels et al., 1998) with P. mettami.