Dorylaimellus chakpilus Mohilal, Gambhir & Dhanachand, 2000

Kumar, Sumit & Ahmad, Wasim, 2024, Description of five new and four known species of Dorylaimellus Cobb, 1913 with perioral disc (Nematoda: Belondiroidea) from the Western Ghats of India, European Journal of Taxonomy 925 (1), pp. 1-45 : 14-15

Dorylaimellus chakpilus Mohilal, Gambhir & Dhanachand, 2000

Fig. 5 , Table 4

Dorylaimellus (Belondorylaimellus) chakpilus Mohilal, Gambhir & Dhanachand, 2000: 55–57 .

Material examined

INDIA • 13 ♀♀; Karnataka State, Hassan district, village Yaraganalu ; 13°08′03.5″ N, 76°18′31.4″ E; 10–15 cm deep; Oct. 26, 2018; soil samples collected from around the roots of grasses (unidentified); slide reference number AMU/ZD/NC / Dorylaimellus chakpilus /1–9 .

Description

Female

Body slightly curved ventrad upon fixation, 0.6–0.8 mm long. Cuticle with transverse striations, about 1 µm thick throughout length of body. Lateral chords 5–7 µm or about one-third to two-fifths (30–40%) of the body diameter at mid-body, glandular bodies weakly developed, about 20–34 in number; 4–9 in pharyngeal region, 4–8 from pharyngeal base to vulva, 8–19 from vulva to anal region and 1–2 in caudal region. Ventral body pores distinct, about 22–28 in number; 5–9 in pharyngeal region, 6–8 from pharyngeal base to vulva and 10–13 from vulva to anal region; lateral and dorsal body pores indistinct. Lip region cap-like, distinctly offset, about 2.0–2.3 times as wide as high, or about one-third to two-fifths (33–40%) of body diameter at neck base. Lips rounded, amalgamated; perioral disc distinct. Cheilostome a truncate cone with refractive walls and distinct cuticularized pieces near oral aperture. Amphids fovea cup-shaped, aperture occupying about 0.6–0.7 times lip region diameter, fusus at level of odontophore base. Guiding ring single, weakly developed, at 0.6–0.8 times lip region diameter from anterior end. Odontostyle comparatively slender, slightly fusiform, 4–5 times as long as wide, about 0.7–0.8 times as long as lip region diameter, its aperture occupying about one-third of length. Odontophore with moderately developed basal flanges, 2.0–2.7 times as long as odontostyle. Nerve ring encircling anterior slender part of pharynx at 30–33% of neck length from anterior end. Pharyngeal expansion gradual; expanded part 9.5–13 times as long as wide, or about 5.2–7.3 times as long as body diameter at neck base, occupying about 48–56% of total neck length, enclosed in thick dextrally spiral muscular sheath. Only dorsal pharyngeal gland and orifice visible: DO =52–57; DN =54–59; DO– DN =1.5–3.4. Cardia short, hemispheroid, 1.0–1.8 times as long as wide, occupying about two-sevenths to two-fifths (28–43%) of corresponding body diameter.

Genital system amphidelphic, both branches almost equally developed. Ovaries reflexed, rarely reaching oviduct-uterus junction, measuring 17–91 µm (anterior) and 19–73 µm (posterior) long, with oocytes arranged in single row except near tip. Oviduct joining ovary subterminally, anterior 15–28 µm or 0.8–1.6 times, and posterior 16–31 µm or 0.9–1.8 times as long as mid-body diameter, consisting of a slender part with prismatic cells and a wider pars dilatata with distinct lumen; oviduct-uterus junction marked with sphincter. Uterus a small tube, anterior 5–12 µm or 0.3–0.8 times, and posterior 6–13 µm or 0.4–0.7 times as long as corresponding body diameter; sperms not observed. Vulva longitudinal. Vagina extending inwards about one-third to one-half (33–50%) of corresponding body diameter; pars proximalis vaginae longer than wide, 4–6×3.0 µm, with convex walls; pars refringens absent; pars distalis 1–2 µm. Prerectum 5.1–8.1 and rectum 1.3–1.9 times as long as anal body diameter. Tail slightly ventrally curved, subcylindrical, tapering gradually to a broadly rounded terminus.

Male

Not found.

Remarks

Mohilal et al. (2000) described D. chakpilus from around the roots of Cynodon dactylon (dhoob grass) from Manipur, India, and differentiated it from D. paralongicaudatus Hussain & Khan, 1967 (now D. longicaudatus Jairajpuri, 1964 ) and D. parvus Jairajpuri, 1965 . The present specimens from Karnataka conform well with the type population except for having a slightly longer body (L=0.6–0.8 vs 0.57–0.6 mm), in the presence of weak lateral glandular bodies (vs indistinct),distinct ventral body pores (vs indistinct); wider lip region (6–7 vs 5.2 µm), a shorter odontostyle (4–5 µm vs 5.6–7.2 µm or 0.7–0.8 vs slightly longer than lip region diameter), and a slightly longer odontophore (10–11 vs 8.0–9.6 µm); however, the combined odontostyle-odontophore length is almost the same. In the original description, the shape of the vulva has been mentioned as transverse; however, in the figure ( Mohilal et al. 2000 fig 2e) it appears longitudinal. The present specimens also have a longitudinal vulva.

Figures

Fig. 5. Dorylaimellus chakpilus Mohilal, Gambhir & Dhanachand, 2000 (LM photographs). A– B. Anterior region, arrow in A indicating basal flanges. C. Anterior end showing amphid. D. Arrows indicating body pores. E. Expanded part of pharynx. F. Vulva region. G. Female genital system. H. Posterior end. Scale bars: A–H=10 µm.