Basirotyleptus neocaudatus, 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 : 39-44

Basirotyleptus neocaudatus sp. nov.

urn:lsid:zoobank.org:act:E9DD76EF-C8B7-450B-B019-F77513AE8C42

Figs 14–15 , Table 10

Diagnosis

Basirotyleptus neocaudatus sp. nov. is characterized by having 0.31–0.44 mm long body; lip region cap-like, offset by constriction; lips rounded, inner part slightly elevated; odontostyle 7.5–9.5 μm long, odontophore 10–13 μm long, total stylet length 18–22 μm; pharynx a slender anterior part, expanding abruptly into a short pyriform basal bulb, occupying about 14–19% of total neck length; female genital system monodelphic-opisthodelphic; anterior genital branch absent or rarely a very small sac, 3.0– 5.0 µm or less one-third midbody diameter long, tail with convex-conoid to digitate acute terminus, 1.1–1.7 times anal body diameter long; male with 20.5 µm long spicules, 5.5 µm long lateral guiding pieces and two ventromedian supplements.

Etymology

The new species is named Basirotyleptus neocaudatus sp. nov. because of its tail close to B. caudatus .

Material examined

Holotype INDIA • ♀; Kerala State, Kasaragad district, Ranipuram National Park ; 12.4º26′18.3″ N, 75.3º58′94.4″ E; 5–15 cm depth; 7 Nov. 2016; soil samples collected from around the roots of grasses (unidentified); slide reference number AMU/ZD/NC/ Basirotyleptus neocaudatus /1.

Paratypes INDIA • 5 ♀♀, 1 ♂; same collection data as for holotype; slides reference number AMU/ZD/NC/ Basirotyleptus neocaudatus /2–4 .

Additional material

INDIA – Kerala State • 14 ♀♀; Palakkad district, Mukkali Forest ; 11°03′40.7″ N, 76°32.7′23.8″ E; 5–15 cm depth; 26 Oct. 2017; soil samples collected from around the roots of grasses (unidentified); slides reference number AMU/ZD/NC/ Basirotyleptus neocaudatus /5–9 • 16 ♀♀; Idukki district , Muttam; 9°49′22.8″ N, 76°43′40.8″ E; 5–15 cm depth; 30 Oct. 2017; soil samples collected from around the roots of grasses (unidentified); slides reference number AMU/ZD/NC/ Basirotyleptus neocaudatus /10–15.

Type habitat and locality

Soil samples collected from around the roots of grasses (unidentified) from Ranipuram National Park, Kasaragad district, Kerala State.

Other habitat and localities

Soil samples collected from around the roots of grasses (unidentified) from Mukkali forest, Palakkad district and from Muttam, Idukki district, Kerala State.

Description

Female

Small sized nematodes, slightly 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, 1.0–1.5 µm thick at anterior region, 1.5–2.0 µm at midbody and 2.0–2.5 μm on tail. Outer cuticle thin, with fine transverse striations; inner layer thick, its outline loose, irregular, distinctly striated, with distinct radial refractive elements. Lateral chords occupying about 25–35% of midbody diameter. Lateral body pores distinct; one at odontostyle-odontophore region; 1–2 in neck region; 2–3 at neck to vulval region and 3–9 at post-vulval region. Dorsal and ventral body pores indistinct. Lip region cap-like, offset by constriction, 2.0–2.3 times as wide as high or about two-fifths of the body diameter at neck base. Lips slightly angular, separated, inner part slightly elevated. Labial and cephalic papillae distinct but not interfering with labial contour. Amphids 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 slender, solid, needle-like, 1.0–1.4 times the lip region diameter long. Odontophore simple, sclerotized, slightly swollen at base surrounded by pharyngeal tissue, 1.2–1.5 times the odontostyle length. Guiding ring simple, refractive, at 1.1–1.4 times the lip region diameter from anterior end. Pharynx consisting of a slender anterior part, expanding abruptly into a short pearshaped basal bulb, with a perceptible thickening at the posterior part of its inner lining, occupying about 14–19% of total neck length. Nerve ring at 49–64% of neck length from anterior end. Cardia rounded to conoid, about one-sixth to one-third of the corresponding body diameter long.

Genital system monodelphic-opisthodelphic. Ovary reflexed, measuring 33–69 μm; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 27–52 μm, consisting of a slender distal portion and a well-developed pars dilatata. Oviduct-uterus junction marked by weak sphincter. Uterus short and tubular, measuring 13–25 μm. Anterior genital branch completely absent or rarely reduced to a very small sac, less than one-third midbody diameter long. Vagina cylindrical, extending inwards, 9.0–12.0 μm or about one-half to three-fifths (50–61%) of midbody diameter; pars proximalis vaginae 5.5–8.0 × 3.5–5.5 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 2.2–4.7 and rectum 0.9–1.5 times anal body diameter long. Tail convex-conoid to digitate with acute terminus, 1.1–1.7 times anal body diameter long, with a pair of caudal pores on each side.

Male

General morphology similar to that of female except for posterior region being more ventrally curved. Genital system diorchic, testes opposed, sperm cell spindle-shaped. In addition to adcloacal pair at 7 µm from cloacal aperture, there are two irregularly spaced ventromedian supplements, first one located beyond the range of spicules, 19 μm from adcloacal pair and second 15 µm from first. Spicules typically dorylaimoid, curved ventrad, slightly robust, 5.3 times as long as wide and 1.2 times as long as cloacal body diameter, dorsal contour regularly convex, ventral contour bearing a moderately developed hump and hollow, curvature 129º, head occupying 13% of total spicules length, median pieces 12 times as long as wide or occupying 35% of the spicules maximum width, reaching the spicules tip, posterior end 2 μm wide. Lateral guiding pieces distinct, rod-like, about 5.5 times as long as wide or about one-fourth of the spicules length. Prerectum 3.7 and rectum 1.4 times cloacal body diameter long. Tail convex-conoid with acute terminus, about one cloacal body diameter long, with a pair of caudal pores on each side.

Remarks

In the presence of a short body and conoid tail with acute terminus, the new species comes close to B. caudatus Jairajpuri, 1966 and B. conicaudatus sp. nov. but, differs from the former in the absence of liplets (vs present); differently shaped amphids (stirrup-shaped vs cup-shaped); shorter odontostyle (7.5–9.5 vs 12 µm); odontophore longer than odontostyle (vs odontophore shorter than odontostyle, about one-half as long as odontostyle length) and presence of male (vs male absent).

From B. conicaudatus sp. nov., the new species differs in having a simple odontophore, without basal flanges (vs with distinct basal flanged); absence of anterior uterine sac (vs anterior uterine sac present); anterior vulva position (V = 41–48 vs 55–58) and more ventromedian supplements (2 vs 1).

In the presence of a conoid tail, the new species also comes close to B. lieberi Goseco et al., 1974 and B. westralis Siddiqi, 1970 but differs from the former in having shorter body (L = 0.31–0.44 vs 0.67–0.90 mm); female genital system mono-opisthodelphic (vs mono-prodelphic) and smaller spicules (20.5 vs 24–28 µm).

From B. westralis , the new species differs in having shorter body (L = 0.31–0.44 vs 0.55–0.75 mm); female genital system mono-opisthodelphic (vs amphidelphic) and smaller spicules (20.5 vs 22–25µm).

Figures

Fig. 14. Basirotyleptus neocaudatus sp. nov. A, C, E–F, I. Holotype, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/1). B, H. Paratype, ♂ (AMU/ZD/NC/Basirotyleptus neocaudatus/4). D. Specimen 10, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/6). G. Paratype 1, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/2). A. Entire female. B. Entire male. C. Female, anterior region showing amphid. D–E. Female, anterior region. F. Female, pharyngeal region. G. Female, genital system. H. Male, posterior region. I. Female, posterior region.

Fig. 15. Basirotyleptus neocaudatus sp. nov. (LM photographs). A, C–D, J–M. Paratypes (AMU/ ZD/NC/Basirotyleptus neocaudatus/2–4). A, D. Paratype 6, ♀. B. Specimen 14, ♀ (AMU/ZD/NC/ Basirotyleptus neocaudatus/9). C. Paratype 4, ♀. E. Specimen 21, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/11). F. Specimen 24, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/12). G. Specimen 25, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/12). H–I. Holotype, ♀ (AMU/ZD/NC/Basirotyleptus neocaudatus/1). J. Paratype 2, ♀. K. Paratype 1, ♀. L–M. Paratype, ♂. A–C. Female, anterior region. D. Female, anterior region showing amphid. E. Female, pharyngeal region. F–G. Female, pharyngeal bulb. H. Female, genital system. I. Vulval region. J. Female, posterior region. K. Female, posterior end. L. Male, posterior region. M. Male, posterior end. Scale bars =10 µm.