Tylencholaimus orientalis, Li & Baniyamuddin & Ahmad & Wu, 2008

Li, Yujuan, Baniyamuddin, M., Ahmad, Wasim & Wu, Jihua, 2008, Four new and four known species of Tylencholaimoidea (Dorylaimida: Nematoda) from China, Journal of Natural History 42 (29 - 30), pp. 1991-2010 : 1993-1995

Tylencholaimus orientalis sp. nov.

( Figure 1 A–F; Table 1)

Description

Female. Body curved, ventrad upon fixation tapering slightly towards anterior extremity. Cuticle thin and with very fine transverse striations; inner layer irregular with distinct striation, 1.0 mm thick at mid body and 1.0–2.0 mm on tail. Lateral chords about one-third of body width at mid body. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, low, offset by constriction, about one-half as wide as high or about one-third as wide as body width at neck base. Lips amalgamated; labial and cephalic papillae not interfering with the labial contour. Amphids stirrup-shaped with aperture occupying about one-third of the lip region width. Odontostyle 0.7–0.8 lip-region-width long, its aperture about one-third of its length. Guiding ring ‘single’, at 0.5–0.6 lip-region-width from anterior end. Odontophore rod-like with small basal knobs, 1.1–1.2 times the odontostyle length. Nerve ring encircling the anterior slender part of pharynx at 40–41% of neck length from anterior end. Pharyngeal expansion gradual; expanded part occupying about 44–45.5% of total neck length. Cardia short, cylindrical, conoid, about onequarter to one-third of corresponding body-width long. Pharyngeal gland nuclei located as follows: D564–68; AS 1525–29; AS 2538–43; PS1572–75; PS2575–81. Genital system monoprodelphic; posterior genital branch represented by a small uterine sac. Anterior genital branch well developed. Ovary reflexed, measuring 26– 69 mm, with oocytes arranged in a single row except near tip. Oviduct joining the ovary subterminally, measuring 38–87 mm. Sphincter between oviduct and uterus present. Uterus a small tube measuring 30–54 mm. Vulva transverse. Vagina extending inward, about two-thirds of corresponding body width deep; pars proximalis vaginae 7–9 mm long, encircled by circular muscles; pars refringens vaginae absent; pars distalis vaginae 3.5–4.5 mm, with rounded walls. Prerectum 4.3– 5.1 anal-body-widths long. Rectum about 0.92–1.2 anal-body-widths long. Tail short, conoid to hemispheroid, 0.70–1.0 anal-body-widths long, with finely rounded terminus. Caudal pores two on each side.

Male. Not found.

Type habitat and locality

Soil around the roots of trees in a mixed evergreen broad-leaved forest, Ailao Mountains, Yunnan Province, China.

Type specimens

Holotype female on slide T. orientalis sp. nov. /1; paratype females on slides T. orientalis sp. nov. /2–5, deposited with the nematode collection of the Department of Zoology, Aligarh Muslim University, India. Paratype females on slides T. orientalis sp. nov. /6–8 with Fudan University, China.

Diagnosis and relationships

Tylencholaimus orientalis sp. nov. is characterized by having 0.45–0.61 mm long body; offset lip region; 5–6 mm long odontostyle; odontophore with small basal knobs; pharyngeal expansion gradual; monoprodelphic genital system with a short post-uterine sac, and short conoid to hemispheroid tail.

With a monoprodelphic genital system, relatively short odontostyle, small amphid and gradual pharyngeal expansion, the new species is most closely related to T. maritus Loof and Jairajpuri, 1968 and T. australis Yeates, 1979 ; however, it differs from the former in having a longer odontostyle and odontophore (combined odontostyle and odontophore length 11–13 vs 9–10 mm), a more posterior vulva position (vs V560–63), a longer post-uterine sac (vs 6–9.5 mm), and a shorter tail (vs tail 15–16 mm, c951.1–1.3).

From T. australis , the new species differs by having a comparatively longer odontostyle and odontophore (vs odontostyle 4.5 mm; combined odontostyle and odontophore 11–13 vs 9.5 mm), shorter cardia (vs 10.5 mm); shorter and differently shaped tail (vs tail convex, conoid with slightly sunken tip, vs 14–16 mm long). The new species is also related to T. ibericus Peña-Santiago and Coomans, 1994 but differs in the presence of a posterior uterine sac (vs completely absent).

Figures

Figure 1. (A–F) Tylencholaimus orientalis sp. nov.: (A) anterior region; (B) anterior end showing amphid; (C) expanded part of pharynx; (D) female genital branch; (E,F) female posterior ends. (G–K) Tylencholaimus proximus Thorne, 1939: (G) anterior region; (H) anterior end showing amphid; (I) expanded part of pharynx; (J) female genital branch; (K) female posterior region.