Dorylaimellus (Axodorylaimellus) parvulus 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 : 2808-2812

Dorylaimellus (Axodorylaimellus) parvulus Thorne, 1939

( Figures 11 and 12 A–D; Table 6)

Description

Female. Body curved ventrad upon fixation, tapering towards both extremities. Cuticle with fine transverse striations, 2.0– 2.5 µm thick at mid body and 3–4 µm on tail. Lateral chords with weak glandular bodies, about one-third as wide as body width at mid body. Lateral, dorsal and ventral body pores indistinct. Lip region offset, about twice as wide as high or about one-third as wide as body width at neck base; peri-oral disc present. Cheilostome a truncate cone with refractive walls and cuticularized plates around oral aperture. Amphids cup-shaped, with wide aperture covering almost entire lateral surface at that level. Odontostyle about 0.8–1.0 lip region width long, its aperture about one-third of its length. Odontophore flanged, 1.4–1.6 times the odontostyle length. Nerve ring at 38–40% of neck length from anterior end. Pharyngeal expansion abrupt; expanded part occupying about 48–57% of total neck length, enclosed in a thick sheath of dextrally spiral muscles. Cardia short, conoid, about one-third to one-half of the corresponding body width long. Genital system amphidelphic; both the sexual branches almost equally developed. Ovaries reflexed, measuring 12–13 µm (anterior) and 12–14 µm (posterior) with oocytes arranged in a single row except near tip. Oviduct joining ovary subterminally, measuring 8–10 µm (anterior) and 10–12 µm (posterior). Sphincter at oviduct–uterus junction weakly developed. Uterus a small tube, measuring 13–15 µm (anterior) and 12–15 µm (posterior). Vulva transverse. Vagina extending inward, about one-third of corresponding body width; pars proximalis vaginae 3–5 µm with curved walls; pars refringens vaginae absent; pars distalis vaginae 1.0– 1.2 µm with rounded walls. Prerectum about 3.5–6.0 times anal body width long. Rectum about as long as anal body width. Tail short, hemispheroid with thick terminal cuticle, 1.3–1.6 times anal body width. Caudal pores two on each side.

Male. Not found.

Habitat and locality

From soil around the roots of forest trees (unidentified), from Kaziranga National Park , Assam; 26 ◦ 36 ′ 0 ′′ N, 93 ◦ 28 ′ 0 ′′ E, altitude 60 m above sea level .

Remarks

Thorne (1939) described D. parvulus from USA. Later, this species was reported from India ( Jairajpuri 1964), the Netherlands ( Bongers 1988) and Venezuela ( Loof 1964). Peralta and Peña-Santiago (2000) provided a detail description of D. parvulus from the Iberian Peninsula and also synonymized Dorylaimellus caffrae with it. The present specimens though slightly smaller (vs L = 0.45–0.57 mm) correspond well with the earlier descriptions.

Figures

Figure 11. Dorylaimellus (Axodorylaimellus) parvulus Thorne, 1939. (A) Entire female, (B) anterior region, (C) anterior end showing amphid, (D) pharyngeal region, (E) expanded part of pharynx, (F) female genital system, (G) vulval region, (H) female posterior region showing prerectum, (I) female posterior region.

Figure 12. (A-D) Dorylaimellus (Axodorylaimellus) parvulus Thorne, 1939. (A) Anterior region, (B) expanded part of pharynx, (C) vulval region, (D) female posterior region showing prerectum. (E–H) Dorylaimellus (Axodorylaimellus) deviatus Baqri and Jairajpuri, 1969. (E) Anterior region, (F) expanded part of pharynx, (G) vulval region, (H) female posterior region. Scale bars: A, E = 10 µm; B–D, F–H = 20 µm.