Basirotyleptus siddiqii, Islam & Ahmad, 2022

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 : 44-49

Basirotyleptus siddiqii sp. nov.

urn:lsid:zoobank.org:act:EA6FF0DE-F046-4879-B5C1-A0DC37394D25

Figs 16–17 , Table 11

Diagnosis

Basirotyleptus siddiqii sp. nov. is characterized by having robust body, 0.36 mm long; lip region caplike, low, flat, offset by depression; lips rounded, inner part slightly elevated; odontostyle 7.5–8.0 μm long, odontophore 10.0–10.5 μm long, total stylet length 17.5–18.5 μm; pharynx slender with slightly muscular anterior part, expanding gradually into a short pear-shaped basal bulb, occupying about 15–

16% of total neck length; female genital system monodelphic-opisthodelphic; anterior genital branch reduced to small sac, 4.0–6.0 µm or one-fourth to one-third midbody diameter long, tail short, bluntly rounded, 0.9 times anal body diameter long.

Etymology

The new species is named after late Dr Mohammad Rafiq Siddiqi in recognition of his contribution to nematode taxonomy.

Material examined

Holotype INDIA • ♀; Tamil Nadu State, Nilgiris hill district, Naduvattum ; 11º28′37.8″ N, 76º32′36.7″ E; 5–15 cm depth; 15 Nov. 2016; roots of shrubs (unidentified); slide reference number AMU/ZD/NC/ Basirotyleptus siddiqii /1.

Paratype INDIA • 1 ♀; same collection data as for holotype; slide reference number AMU/ZD/NC/ Basirotyleptus siddiqii /2 .

Type habitat and locality

Soil samples collected from around the roots of shrubs (unidentified) from Naduvattum, Nilgiris Hill, Tamil Nadu State.

Description

Female

Very small size, robust nematodes, curved ventrad or open C-shaped upon fixation; body cylindrical, tapering gradually towards both extremities but more so towards the anterior end. Cuticle with two distinct layers, 1.0 µm thick at anterior region, 1.5 µm at midbody and 2.0 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, finely striated, loose, with radial refractive elements. Lateral chords occupying about 22–24% of midbody diameter. Lateral, dorsal and ventral body pores indistinct. Lip region cap-like, low, flat, offset by depression, 2.5 times as wide as high or about two-fifths of the body diameter at neck base. Lips rounded, amalgamated, inner part slightly elevated. Amphids stirrup-shaped, their aperture about two-thirds as wide as lip region diameter. Stoma a long, slender truncate cone, slightly sclerotized in the perioral region. Odontostyle short, slender, solid, needle-like, 1.0–1.1 times the lip region diameter long. Odontophore simple, sclerotized, with basal flanges, about 1.3 times the odontostyle length. Guiding ring simple, refractive, at 1.0–1.1 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding gradually into a short pearshaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 15–16% of total neck length. Nerve ring at 52–53% of neck length from anterior end. Cardia rounded to conoid, about one-fourth of the corresponding body diameter long.

Genital system monodelphic-opisthodelphic. Ovary reflexed, measuring 42–53 μm; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 36–42 μm, consisting of a slender distal portion and a well-developed pars dilatata. Oviduct-uterus junction marked by distinct sphincter. Uterus short and wide tubular, measuring 17–18 μm. Anterior genital branch reduced to a small sac, 4.0–6.0 μm or one-fourth to one third of midbody diameter. Sperms absent. Vagina cylindrical, extending inwards, 9.5 μm or about one-half (53%) of midbody diameter; pars proximalis vaginae 6.0– 6.5 × 4.0–4.5 μm, encircled by circular muscles; pars distalis 3.5–4.0 μm with slightly curved walls; pars refringens absent. Vulva apparently a transverse slit. Prerectum 6.0–6.8 and rectum 1.2–1.4 times anal body diameter long. Tail short, conoid, 0.8–0.9 times anal body diameter long, with a pair of caudal pores on each side.

Male

Not found.

Remarks

In its small body size and flanged odontophore, the new species comes close to B. siremps Siddiqi, 1995 ; B. syncheilus Siddiqi, 1995 and B. minutus Siddiqi, 1995 but it differs from B. siremps in having low, flat lip region, offset by depression (vs lip region high, conoid, offset by constriction); cuticle finely striated (vs cuticle distinctly striated); slightly longer odontophore (10.0–10.5 vs 8.0–9.0 µm); slightly posterior vulva position (V = 54–56 vs 47–53); in the shape and size of tail (conoid vs subcylindrical to a hemispherical terminus; c’ = 0.9 vs 1.2–1.7) and absence of male (vs male present).

From B. syncheilus , the new species differs in having lip region low, wider, offset by depression (vs lip region narrow, 5.0 µm, continuous with body); lips slightly raised (vs lips not raised); shorter odontostyle (7.5–8.0 vs 9.0–1.0); shorter pharyngeal bulb (15–16 vs 19 µm); shorter anterior uterine sac (4.0–6.0 µm or 0.2–0.3 vs 18 µm or about one midbody diameter) and absence of male (vs male present).

From B. minutus , the new species differs in having slightly short and slender body (L = 0.36 vs 0.38– 0.51 mm; a = 20–21 vs 23–39); amphids simple (vs duplex); shorter total stylet (17.5–18.5 vs 23–24 µm, odontostyle 7.5–8.0 vs 10 µm, odontophore 10.0–10.5 vs 13–14 µm), posterior vulva position (V = 54–56 vs 32–42) and presence of anterior uterine sac (vs absent).

The new species also comes close to B. diminutus Siddiqi, 1995 but differs in having differently shaped lip region (lip region flat, low, offset by depression vs lip region conoid, high, offset by constriction); odontophore with distinctly basal flanges (vs poorly basal flanges), posterior vulva position (V = 54–56 vs 37–42) and presence of anterior uterine sac (vs absent).

Figures

Fig. 16. Basirotyleptus siddiqii sp. nov., ♀. A–B, D–G. Holotype (AMU/ZD/NC/Basirotyleptus siddiqii/1). C. Paratype 1 (AMU/ZD/NC/Basirotyleptus siddiqii/2). A. Entire specimen. B–C. Anterior region. D. Anterior region showing amphid. E. Pharyngeal region. F. Genital system. G. Posterior region.

Fig. 17. Basirotyleptus siddiqii sp. nov., ♀ (LM photographs). A–B, E, I–K. Holotype (AMU/ZD/ NC/Basirotyleptus siddiqii/1). C–D, F–H. Paratype 1 (AMU/ZD/NC/Basirotyleptus siddiqii/2). A. Entire specimen. B–C. Anterior region. D. Pharyngeal region. E. Anterior region showing amphid. F. Pharyngeal bulb. G. Vulval region. H–I. Genital system. J. Posterior region. K. Posterior end. Scale bars: A = 20 µm; B–K = 10 µm.