Paramphimonhystrella Huang & Zhang, 2006

Leduc, Daniel, 2014, Four new Paramphimonhystrella species (Nematoda: Xyalidae) from the continental slope of New Zealand, Zootaxa 3814 (4), pp. 478-494 : 479

Genus Paramphimonhystrella Huang & Zhang, 2006

Type species: P. elegans Huang & Zhang, 2006

Diagnosis (modified from Huang & Zhang (2006)). Cuticle smooth or striated. Head tapering. Buccal cavity deep, either funnel-shaped, lozenge-shaped, or with cylindrical anterior portion and funnel-shaped posterior portion, with cuticularised walls; teeth absent. Two rings of 8–16 sub-cephalic setae; first ring situated at level of, or just posterior to amphid, second ring 0.5–2.0 cbd further posteriorly. Circular or ovoid amphid with cuticularised outline. Spicules short or long; gubernaculum usually absent; no pre-cloacal supplements. Male with both testes either to the right or left of intestine. Females sometimes with hammer-shaped cuticularised piece situated immediately posterior to vagina; postvulvar sac often present and elongated. Three caudal glands, one or two of which is markedly larger than the other(s), sometimes giving tail a swollen appearance.

Remarks. The genus Paramphimonhystrella is similar to Amphimonhystrella in the arrangement of head sensillae, shape of the buccal cavity and female reproductive system with long postvulvar sac. The two genera can be differentiated from each other mainly based on (1) the number and arrangement of sub-cephalic setae, and (2) the relative size of the caudal glands. In Paramphimonhystrella , two circles of 8–16 sub-cephalic setae are present, whereas in Amphimonhystrella sub-cephalic setae are either absent or only one circle of four sub-cephalic is present slightly posterior to the amphids. In addition, at least one of the caudal glands in Paramphimonhystrella has a conspicuously swollen appearance, which is not the case in Amphimonhystrella . The two genera also differ in body length, with all three Amphimonhystrella species measuring ~500 µm or less, whereas Paramphimonhystrella species measure 740–1916 µm.