Dorylaimellus (Dorylaimellus) occidentalis Thorne, 1939

Ahmad, Wasim & Naz, Tabbasam, 2012, Four new and six known species of the genus Dorylaimellus Cobb, 1913 (Nematoda: Belondiridae) from India, Journal of Natural History 46 (45 - 46), pp. 2787-2828 : 2805-2808

Dorylaimellus (Dorylaimellus) occidentalis Thorne, 1939

( Figures 9 and 10 ; Table 5)

Description

Female. Body curved ventrad upon fixation, tapering towards both extremities. Cuticle with fine transverse striations, 1.0– 1.5 µm thick at mid body and 5.0 µm on tail. Lateral chords occupying about one-third of corresponding body width at mid body with about 50–60 glandular organs. Lateral, dorsal and ventral body pores indistinct. Lip region offset, twice as wide as high or about one-third as wide as body width at neck base. Cheilostome a truncate cone with refractive walls and cuticularized plates around oral aperture. Amphids stirrup-shaped, their apertures occupying about 0.7–0.8 times lip region width. Odontostyle about 1.0–1.1 times lip region width long, its aperture about one-third of its length. Odontophore rod-like with basal flanges, 1.6–1.7 times the odontostyle length. Nerve ring at 24–26% of neck length from anterior end. Pharyngeal expansion abrupt; expanded part occupying about 52–64% of total neck length, enclosed in a thick sheath of dextrally spiral muscles. Cardia short, rounded, about one-half of the corresponding body width long. Genital system amphidelphic; both the sexual branches almost equally developed. Ovaries reflexed, measuring 18–33 µm (anterior) and 25–28 µm (posterior) with oocytes arranged in a single row except near tip. Oviduct joining ovary subterminally, measuring 24–35 µm (anterior) and 20 µm (posterior) long. Uterus a small tube, measuring 20–25 µm (anterior) and 20–30 µm (posterior). Vulva longitudinal. Vagina extending inward, about one-third of the corresponding body width deep; pars proximalis vaginae 6–7 µm with slightly convex walls; pars refringens vaginae absent; pars distalis vaginae 1.5 µm with rounded walls. Prerectum about 5–7 times anal body width long. Rectum about 1.0–1.3 times anal body width long. Tail short conoid with rounded terminus, 1.6–1.9 times anal body width long. Caudal pores two on each side.

Male. Not found.

Habitat and locality

From soil around the roots of Acacia forest, Agra road, Aligarh; 27 ◦ 53 ′ 0 ′′ N, 78 ◦ 4 ′ 0 ′′ E, altitude 187 m above sea level.

Remarks

Thorne (1939) describes D. occidentalis from Idaho, USA. The present population from India conforms well to the original description except for having a slightly longer tail (c = 30–36 vs 36). Dorylaimellus occidentalis is closely related to Dorylaimellus vexator Heyns, 1963 in body size and its long expanded part of pharynx but differs in having longer and relatively slender odontostyle (odontostyle more than one lip region width vs less than one lip region width), and in having differently shaped tail (elongate conoid vs bluntly rounded). This species is reported for the first time from India.

Figures

Figure 9. Dorylaimellus (Dorylaimellus) occidentalis Thorne, 1939. (A) Entire female, (B) anterior region, (C) anterior end showing amphid, (D) pharyngeal region, (E) female genital system, (F) mid body showing lateral hypodermal glands, (G) female posterior region showing prerectum, (H) female posterior region.

Figure 10. Dorylaimellus (Dorylaimellus) occidentalis Thorne, 1939. (A) Anterior region, (B) anterior end showing amphid, (C) junction between two parts of pharynx, (D) pharyngoinstestinal junction, (E) vulval region, (F,G) female posterior region. Scale bars: A–G = 20 µm.