Tylencholaimus sp.

Ahmad, Wasim, Park, Byeong-Yong, Lee, Jae-Kook & Choi, Dong-Ro, 2009, Some new and known species of Tylencholaimoidea (Nematoda: Dorylaimida) from Korea, Journal of Natural History 43 (37 - 38), pp. 2329-2356 : 2342

Tylencholaimus sp.

( Figures 4A–E , 5A–E ; Table 3)

Description

Female. Body slightly curved ventrad upon fixation, tapering slightly towards anterior extremity. Cuticle thin, finely striated; inner layer with distinct but fine transverse striations, slightly irregular and loosened from the outer layer. Radial refractive elements indistinct. Lateral chords about one-third of body width at midbody. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, rather flattened, offset by slight constriction. Lips amalgamated; labial and cephalic papillae not interfering with the labial contour. Amphid small, cup-shaped with slit-like aperture about one-third of the lip region width. Odontostyle relatively slender, about as long as lip region width; its aperture about one-quarter of its length. Guiding ring single, at 0.8 times the lip region width from anterior end. Odontophore rod-like, as long as odontostyle length with indistinct basal knobs. Anterior part of pharynx slender, weakly muscular, expanding abruptly into a long cylindrical basal bulb, occupying 37.5% of total neck length. Nerve ring encircling anterior slender part of pharynx at 43.7% of neck length from anterior end. DN close to DO; S1N near middle of expanded part; S2N distinct. Cardia short, conoid. Genital system didelphic–amphidelphic; both the branches almost equally developed. Ovaries reflexed, measuring 50 µm (anterior) and 47 µm (posterior) with oocytes arranged in a single row except near tip. Oviduct joining ovary subterminally, 43 µm (anterior) and 37 µm (posterior) long. Uterus a small tube, 15 µm (anterior) and 16 µm (posterior) long. Sphincter almost indistinct. Vagina extending about 60% of the corresponding body width deep. Pars proximalis vaginae with straight walls encircled with circular muscles; pars refringens vaginae absent; pars distalis vaginae 3 µm long. Prerectum 2.9 anal body widths long. Rectum as long as anal body width. Tail short, dorsally convex conoid, almost cylindroid with a pair of caudal pore on each side.

Male. Not found.

Habitat and locality

Soil around roots of forest trees from Uleungdo, Gyeongsangbuk-do, South Korea.

Remarks

This single specimen, because of its characteristic features, differs from all the amphidelphic species of the genus Tylencholaimus , and probably represents a new species. However, it is generally not advisable to designate a new species based on a single specimen so we are hesitant in giving it a new name and refer to it simply as Tylencholaimus sp.

In the nature of its pharynx and in having an amphidelphic gonad, this single specimen resembles T. savaryi Loof and Jairajpuri, 1968 but differs in having smaller body size (versus 0.70–0.80 mm); in the shape of lip region (versus lip region distinctly offset with projecting lips); smaller amphids (versus amphid aperture about half to twothirds of lip region width); longer and slender odontostyle (versus 5–6 µm long rather robust odontostyle); in the nature of the odontophore base (versus odontophore with minute oblong basal knobs); and in having a longer tail (verus c′ = 0.9–1.2).

Figures

Figure 4. (A–E) Tylencholaimus sp. (A) Anterior region; (B) anterior end showing amphid; (C) expanded part of pharynx; (D) female genital system; (E) female posterior region. (F–J) Tylencholaimus intermedius Peña-Santiago and Coomans, 1996. (F) Anterior end; (G) anterior end showing amphid; (H) expanded part of pharynx; (I) female genital region; (J) female posterior region.(K–O) Promumtazium pyxidorum Siddiqi, 1982. (K) Anterior region; (L) anterior end showing amphid; (M) expanded part of pharynx; (N) female genital system; (O) female posterior end.

Figure 5. (A–E) Tylencholaimus sp. (A) Anterior region; (B) expanded part of pharynx; (C) female genital system; (D) female posterior region: (E) female posterior end. (F–H) Tylencholaimus intermedius Peña-Santiago and Coomans, 1996. (F) Anterior region; (G) expanded part of pharynx; (H) female genital system.