Tylencholaimus sinensis, 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 : 1995-2000

Tylencholaimus sinensis sp. nov.

( Figure 2 A–F; Table 2)

Description

Female. Body slightly curved, ventrad upon fixation. Outer cuticle smooth, inner cuticle transversely striated, loose, 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, offset by constriction, about onehalf as wide as high or about one-third as wide as body width at neck base. Lips amalgamated. Amphids stirrup-shaped, their apertures occupying about half of lip region width. Odontostyle 0.87 times lip-region-width long, its aperture about onethird of its length. Guiding ring ‘single’, at 0.5–0.6 times lip-region-width from anterior end. Odontophore rod-like with small basal knobs, slightly longer than the odontostyle. Nerve ring encircling the anterior slender part of pharynx at 35–43% of neck length from anterior end. Pharyngeal expansion gradual; expanded part occupying about 35–36% of total neck length. Cardia short, conoid about onequarter to one-third of corresponding body-width long. Pharyngeal gland nuclei located as follows: D564–67%; AS 1526–29%; AS 2549–51%; PS1569–74%; PS2575–80%. Genital system didelphic–amphidelphic. Ovaries reflexed, measuring 45–77 mm (anterior) and 54–59 mm (posterior), with oocytes arranged in a single row except near the tip. Oviduct joining the ovary subterminally, measuring 53–63 mm (anterior) and 45–50 mm (posterior). Sphincter present between oviduct–uterus junctions. Uterus a small tube measuring 50–66 mm (anterior) and 47–52 mm (posterior). Vulva transverse. Vagina directed inward, about one-half of corresponding body-width deep. Pars proximalis vaginae 10–11 mm, with thick walls encircled by circular muscles; pars refringens vaginae absent; pars distalis vaginae 3–5 mm, with rounded walls. Prerectum about five anal body widths long. Rectum about as long as anal body width. Tail short conoid to hemispheroid, 0.80– 0.85 times anal body widths long, with finely rounded terminus. Caudal pores two on each side.

Male. Similar to female in general morphology except the posterior region is more curved ventrally because of the presence of copulatory muscles. Supplements, an adanal pair and three ventromedians. Spicules about 1.5–1.6 times anal body widths long. Lateral guiding pieces about one-quarter of spicule length. Prerectum four times anal-body-width long. Rectum about 1.2–1.3 times anal-body-width long. Tail similar to female short, conoid to hemispheroid, 0.76–0.80 times anal-body-width long, with finely rounded terminus. Caudal pores two on each side.

Type habitat and locality

Soil around the roots from meadows and shrubland in Mila, Sejila Mountains, Tibet, China.

Other habitat and locality

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

Type specimens

Holotype female on slide Tylencholaimus sinensis sp. nov. /1; paratype male on slide Tylencholaimus sinensis sp. nov. /2. A single female and a male from Ailao mountains on slide Tylencholaimus sinensis sp. nov. /3–4; deposited with the nematode collection of the Department of Zoology, Aligarh Muslim University, India.

Diagnosis and relationships

Tylencholaimus sinensis sp. nov. is characterized by having a 0.76–0.82 mm long body; offset, cap-like lip region; 7–7.5 mm long odontostyle; odontophore with small knobs; expanded part of pharynx with gradual expansion; amphidelphic genital system; short conoid to hemispheroid tail, and males with 32 mm long spicules and three ventromedian supplements.

With the amphidelphic genital system, perioral region without disc and gradually expanded pharyngeal region, the new species is closely related to T. teres Thorne, 1939 ; T. crassus Loof and Jairajpuri, 1968 ; T. paracrassus Monteiro, 1970 ; T. suryawanshii Ali and Chisty, 1972 and T. innebus Ahmad and Jairajpuri, 1980 .

It differs from T. teres in having a shorter body (0.76–0.82 vs 0.84–1.05 mm); comparatively wider amphid (4–5 vs 3–4 mm); comparatively longer odontostyle (7– 7.5 vs 5–6 mm); shorter pharyngeal bulb (67–75 vs 81–110 mm; 35–36 vs 40–50% of neck length); shorter prerectum (five anal body widths vs 6.8–9.5 anal body widths long); simple lateral guiding pieces (vs bifid) and to some extent in tail shape (vs tail round conoid to hemispheroid, c545–45.8 vs 54.7–67.3).

From T. crassus , the new species differs by having a more slender body (a527–28 vs 19.7–22.2), smaller expanded part of pharynx (35–36 vs 41–43% of neck length); more posterior vulva position (V557–57.5 vs 51.3–57), longer prerectum (five anal body widths vs 1.2–2.5 anal body widths), shorter and differently shaped tail (hemispheroid vs convex conoid, 17–18 vs 19–24 mm, c545–45.8 vs 32.5–41; c950.85 vs 0.95–1.05).

From T. paracrassus , the new species differs by having a smaller body size (0.76– 0.82 vs 0.92–1.05 mm), shorter odontostyle length (7–8 vs 10–11.5 mm); shorter pharyngeal bulb (67–75 vs 90–106 mm); longer prerectum (105 vs 47–65); shorter and differently shaped tail (hemispheroid vs convex conoid with rounded terminus, female tail 17–18 vs 30–38.5 mm, c545–45.8 vs 34.5–37.3; c950.85 vs 1.1–1.9 and male tail 16–17 vs 28.5–31.5 mm, c550–50.5 vs 30.7–32.4).

From T. suryawanshii , the new species differs by having a longer body (0.76–0.82 vs 0.63 mm), differently shaped lip region (vs lips angular, lips separate), smaller amphidial aperture (one-half lip region vs two-third lip width), more posterior vulva position (V557–57.5 vs 49), higher c value (c545–45.8 vs 41) longer prerectum (5 vs 2 anal body widths long), and presence of males (vs male absent).

From T. innebus , the new species differs by having a larger body size (0.76–0.82 vs 054– 0.68 mm); differently shaped lip region (vs lips angular and labial papillae elevated); smaller amphid aperture (vs two-third of lip region widths); more anterior vulva position (V557–57.5 vs 62–65), higher c and c9 value (c545–45.8 vs 36–41; c950.85 vs 1), longer prerectum (105 vs 26–50 mm) and by the presence of males (vs males absent).

Figures

Figure 2. (A–F) Tylencholaimus sinensis sp. nov.: (A) anterior region; (B) anterior end showing amphid; (C) expanded part of pharynx; (D) female genital branch (posterior); (E) female posterior end; (F) male posterior region. (G–J) Tylencholaimus japonicus Ahmad and Araki, 2003: (G) anterior region; (H) anterior end showing amphid; (I) female genital system; (J) female posterior end.