Stenodorylaimus, Álvarez-Ortega, Sergio & Peña-Santiago, Reyes, 2011

Álvarez-Ortega, Sergio & Peña-Santiago, Reyes, 2011, Re-description of two atypical species of Pungentus Thorne & Swanger, 1936, with proposal of Stenodorylaimus gen. n. (Nematoda, Dorylaimida, Nordiidae), Zootaxa 2799, pp. 49-62 : 60-61

Stenodorylaimus gen. n.

Diagnosis. Nordiidae (but see remarks), Pungentinae . Large nematodes, 3.7–5.1 mm long. Cuticle dorylaimoid. Lip region offset by constriction and narrow, one-fifth to one-third of body diameter at neck base; lips separate or amalgamated. Cheilostom with thick walls and a thin, weakly refractive perioral ring, appearing as two dots in median view. Odontostyle about twice the lip region width long, slender and with short aperture. Guiding ring double. Odontophore rod-like, with small thickenings at its base. Pharynx relatively short, b- ratio over 7; basal expansion occupying about one-half of total neck length. Female genital system didelphic-amphidelphic; uterus long, 3– 4 times the body diameter; pars refringens vaginae present but not heavily sclerotized; vulva an oval transverse opening. Spicules dorylaimid, curved ventrad. Ventromedian supplements slightly irregularly spaced, 14–19 in number and lacking hiatus. Tail rounded conoid, similar in both sexes.

Type species. S. textilis ( Thorne & Swanger, 1936) comb. n. = Dorylaimus textilis Thorne & Swanger, 1936

Pungentus textilis ( Thorne & Swanger, 1936) Thorne, 1939

Other species. S. intertextus ( Thorne & Swanger, 1936) comb. n. = Dorylaimus intertextus Thorne & Swanger, 1936

Pungentus intertextus ( Thorne & Swanger, 1936) Thorne, 1939 Eudorylaimus intertextus ( Thorne & Swanger, 1936) Goodey, 1963

Relationships. In having large size, a comparatively long (about twice the lip region width) and slender odontostyle with short aperture (one-sixth to one-eighth of its total length), and a rounded conoid tail, the new genus resembles those classified under the family Nordiidae Jairajpuri & Siddiqi, 1964 , subfamily Pungentinae Siddiqi, 1969 , especially the genera Pungentus , Enchodelus Thorne 1939 and Californidorus Robbins & Weiner, 1978 . It differs from Pungentus in presenting an uncommon combination of features (see above). From Enchodelus in its larger body (vs up to 2.5 mm), odontostyle more robust (vs thick-walled and with narrower lumen) and shorter (vs well over 1% of body length), shorter neck (vs b- ratio exceptionally more than 6.0) but longer pharyngeal expansion (vs very often up to two-fifths of total neck length), and uterus more simple (vs typically tripartite). And from Californidorus in its shorter and more robust odontostyle (vs several times as long as lip region diameter and slen- der, needle-like), guiding ring double (vs simple), S1N well developed (vs poorly developed) and female genital system didelphic (vs mono-opisthodelphic).

In having relatively narrow lip region and comparatively long odontostyle, it is reminiscent of members of the family Paraxonchiidae Dhanachand & Jairajpuri, 1981, especially the genera Gopalus Khan, Jairajpuri & Ahmad, 1987 and Parapalus Loof & Zullini, 2000 , but all paraxonchiid taxa are smaller (vs body length up to 2.5 mm), have comparatively longer neck (vs b- ratio up to 5) and conical tail.

Finally, in having large size, odontostyle with short aperture (less than half of its total length) and rounded tail, it resembles some genera of the family Qudsianematidae Jairajpuri, 1965 , especially Crassolabium Yeates, 1967 and Labronema Thorne, 1939 , which are also rounded-tailed, but it can be easily separated from these by its more slender and longer odontostyle (vs stronger, seldom longer than 1.5 times the lip region diameter), and shorter neck (vs b- ratio always under 6.0 and very often after 5.0).

Etymology. The genus name derives from the Greek roots stenós = narrow, dóry = lance or spear, and laimós = throat or neck, and refers to its odontostyle nature. It is masculine in gender.

Remarks. The new genus is provisionally classified under Nordiidae for practical purposes, since this family is certainly not a natural (monophyletic) group (for instance, see molecular tree by Holterman et al., 2008), whose true identity should be matter of a revision in depth of the taxon, which, of course, is beyond of the scope of this contribution. Nevertheless, as mentioned from a morphological perspective, Stenodorylaimus gen. n. resembles some nordiid genera.