Basirotyleptus ethiopicus Siddiqi, 1970

Islam, Md Niraul & Ahmad, Wasim, 2022, Description of five new and six known species of the genus Basirotyleptus Jairajpuri, 1964 (Nematoda: Dorylaimida: Tylencholaimoidea) from the Western Ghats, India, European Journal of Taxonomy 791 (1), pp. 1-57 : 13-16

Basirotyleptus ethiopicus Siddiqi, 1970

Fig. 4 , Table 4

Basirotyleptus ethiopicus Siddiqi, 1970: 205–206

Basirotyleptus ethiopicus – Goseco et al. 1974: 11, 20.

Material examined

INDIA – Kerala State • 7 ♀♀; Palakkad district, Silent Valley National Park ; 11º03′49.6″ N, 76º32′17.4″ E; 5–15 cm depth; 26 Oct. 2017; soil samples collected from around the roots of forest trees (unidentified); slides reference number AMU/ZD/NC/ Basirotyleptus ethiopicus /1–5 .

Description

Female

Small sized nematodes, slightly curved ventrad upon fixation; tapering gradually towards both extremities but more so towards anterior end. Cuticle with two distinct layers, 1.0–1.5 µm thick at anterior region, 2.0–2.5 µm at midbody and 2.5–3.0 μm on tail. Outer cuticle thin with transverse striation, inner layer

thick, distinctly striated, loose, its outline irregular, with distinct radial refractive elements. Lateral chords occupying about 30–35% of midbody diameter. Lateral body pores distinct; 1–2 in neck region; 1–2 from pharyngeal base to vulva; 4–7 in post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by slight constriction, 1.8–2.1 times as wide as high or about one-third to two-fifths of the body diameter at neck base. Lips rounded, amalgamated; inner part elevated, forming a perioral disc. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids duplex, stirrup-shaped, their aperture about one-half to three-fifths as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle very slender, solid, thin needle-like, 1.4–1.8 times the lip region diameter long. Odontophore simple, sclerotized, about 1.0–1.2 times the odontostyle length. Guiding ring simple, refractive, at 1.0–1.3 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short, pear-shaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 13–16% of total neck length. Nerve ring at 55–62% of neck length from anterior end. Cardia short, rounded to conoid, about one-fourth to one-third of the corresponding body diameter long.

Genital system monodelphic-opisthodelphic. Ovary reflexed, measuring 36–88 μm; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 30–57 μm, consisting of a slender distal portion and a weakly developed pars dilatata. Oviduct-uterus junction indistinct. Uterus short and tubular, measuring 21–32 μm. Anterior genital branch completely absent. Sperm cell absent. Vagina cylindrical, extending inwards, 8.5–10.5 μm or about two-fifths to one-half (45–55%) of midbody diameter; pars proximalis vaginae 5.0–7.0 × 3.0–4.0 μm, encircled by circular muscles; pars distalis vaginae 3.0–4.0 μm with slightly curved walls; pars refringens absent. Vulva apparently a transverse slit. Prerectum 2.0–2.9 and rectum 0.9–1.4 times anal body diameter long. Tail short, rounded to hemispheroid, 0.7–0.8 times anal body diameter long, with a pair of caudal pores on each side.

Male

Not found.

Remarks

Siddiqi (1970) described B. ethiopicus from the Malawi. Goseco et al. (1974) in their revision of the genus Basirotyleptus made a detailed study of the type material and added a population from Indiana. The morphometrics of present populations conform well with the type population as well as Indiana population except in having slightly wider lip region (6.0–7.5 vs 5.0–6.0 µm); narrower lateral chords (30–35% vs more than 50% of mid body diameter) and slight differently shaped cardia (rounded to conoid vs rounded). These slight differences are considered as intraspecific variability. This species is reported here for the first time from the India.

In the presence of labial disc, this species closely resembles B. nemoralis Siddiqi, 1970 except in having a comparatively robust body (a = 20–25 vs 27–33); shorter pharyngeal bulb (about one vs two corresponding body diameter long); absence of anterior uterine sac (vs present) and differently shaped tail (rounded to hemispheroid vs obtusely rounded).

Figures

Fig. 4. Basirotyleptus ethiopicus Siddiqi, 1970, ♀ (AMU/ZD/NC/Basirotyleptus ethiopicus/1–5) (LM photographs). A–C. Anterior region. D. Anterior region showing amphid. E. Pharyngeal region. F–G. Pharyngeal bulb. H. Genital system. I. Vulval region. J. Posterior region. K. Posterior end. Scale bars =10 µm.

Tables

Table 4. Measurements of Basirotyleptus ethiopicus Siddiqi, 1970. All measurements are in μm and in the form: mean ± s.d. (range).

Characters	Females
n	7
L	439.8 ± 51.9 (388–500)
Body diameter at neck base	17.7 ± 1.2 (16.5–20.5)
Body diameter at mid body	19.6 ± 1.2 (18.5–22.5)
Body diameter at anus	13.3 ± 1.0 (12.5–15.5)
a	21.9 ± 1.2 (20.8–24.8)
b	4.3 ± 0.46 (3.8–5.3)
c	45.2 ± 3.3 (42.2–52.0)
c’	0.71 ± 0.03 (0.70–0.80)
V	40.1 ± 2.3 (36.9–43.6)
G2	20.2 ± 3.2 (16.0–24.7)
Lip region diameter	6.4 ± 0.49 (6.0–7.5)
Lip region height	3.1 ± 0.24 (3.0–3.5)
Amphidial aperture	3.1 ± 0.22 (3.0–3.5)
Odontostyle length	10.1 ± 0.85 (8.5–10.5)
Odontophore length	11.3 ± 0.55 (10.5–12.0)
Total stylet length	21.4 ± 1.2 (19.5–23.0)
Guiding ring from anterior end	7.7 ± 0.88 (7.0–10)
Nerve ring from anterior end	58.9 ± 2.1 (54–61)
Neck length	100.2 ± 4.3 (94–105)
Expanded part of pharynx	15.2 ± 0.88 (14–17)
Cardia length	4.6 ± 0.68 (4.0–6.0)
Posterior genital branch	90.8 ± 16.5 (68–113)
Vagina length	9.6 ± 0.81 (8.5–10.5)
Vulva from anterior end	179.0 ± 12.9 (167–206)
Prerectum length	32.0 ± 2.9 (27–37)
Rectum length	14.4 ± 1.8 (12.5–18.5)
Tail length	9.5 ± 0.68 (9.0–11)