Dorylaimellus kasplateauensis, Kumar & Ahmad, 2024

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 : 32-36

Dorylaimellus kasplateauensis sp. nov.

urn:lsid:zoobank.org:act:91F04E30–6908–4A27-B3B5-CFB9B6F09A86 Figs 12–13 , Table 8

Diagnosis

Dorylaimellus kasplateauensis sp. nov. is characterized by having a 0.68–0.83 mm long body; lip region offset, inner lips elevated forming a perioral disc, sclerotized pieces distinct; odontostyle robust, 6–7 µm long, odontophore 11–14 µm long with weakly developed basal flanges; expanded part of the pharynx occupying about 38–43% of total neck length; female genital system amphidelphic; vulva longitudinal, located at 48–51% of total body length, and tail elongate conoid, ventrally arcuate, with rounded terminus.

Etymology

The new species is named after its type locality.

Material examined

Holotype

INDIA • 1 ♀; Maharashtra State, Satara district, Kas Plateau Reserve Forest ; 17°43′12″ N, 73°49′22″ E; 10–15 cm deep; 13 Apr. 2016; roots of grasses (unidentified); slide reference number AMU/ ZD/NC / Dorylaimellus kasplateauensis /1.

Paratypes

INDIA • 8 ♀♀; same collection data as for holotype; slide reference number AMU/ZD/NC / Dorylaimellus kasplateauensis /2–4 .

Type habitat and locality

Soil samples collected from around the roots of the grasses (unidentified) from Kas Plateau Reserve Forest of Satara district, Maharashtra State, India.

Description

Female

Body curved ventrad upon fixation, 0.68–0.83 mm long. Cuticle with fine transverse striations, more pronounced on tail region, about 1 µm at anterior and mid-body and about 2 µm on tail tip. Lateral chords 6–7 µm wide, about one-fourth to one-third (24–32%) of mid-body diameter with distinct glandular bodies, about 41–49 in number; 5–7 in pharyngeal region, 11–16 from pharyngeal base to vulva, 21–26 from vulva to anal region and 1–2 in caudal region. Ventral body pores distinct, 26–32 in number; 4–8 in neck region, 8–12 from pharyngeal base to vulva region and 13–15 in caudal region; lateral and dorsal body pores indistinct. Lip region cap-like, offset by constriction, 1.7–2.7 times as wide as high, or about one-third to two-fifths (31–40%) of body diameter at neck base. Lips rounded, inner lips elevated forming weak pseudo-perioral disc. Cheilostome a truncate cone with refractive walls and distinct cuticularized pieces near oral aperture. Amphids fovea stirrup-shaped, their aperture occupying about 0.6–0.7 times lip region diameter, fusus just opposite or slightly posterior to odontophore base. Guiding ring at 0.6–0.8 times lip region diameter from anterior end. Odontostyle robust, 6–7 times as long as wide, about 0.7–1.0 times as long as lip region diameter, aperture occupying about one-third of its length. Odontophore with weakly developed basal flanges, 1.6–2.3 times as long as odontostyle. Nerve ring encircling anterior slender part of pharynx at 36– 42% of neck length from anterior end. Pharyngeal expansion abrupt; expanded part 4.2–6.3 times as long as wide, or about 2.4–3.5 times as long as body diameter at neck base, occupying about 38–43% of total neck length, enclosed in dextrally spiral muscular sheath. Only dorsal pharyngeal gland nucleus and its orifice visible: DO =62–66.5; DN= 63.5–67.3; DO–DN = 0.6–1.5. Cardia short, rounded conoid, 0.8–1.4 times as long as wide, occupying about one-fourth to one-third (24–35%) of corresponding body diameter.

Genital system amphidelphic, both genital branch almost equally developed. Ovaries reflexed, not reaching oviduct-uterus junction, measuring 31–46 µm (anterior) and 31–48 µm (posterior) long, with oocytes arranged in single row except near tip. Oviduct joining ovary subterminally, anterior 36–45 µm or 1.6–1.9 times and posterior 25–35 µm or 1.1–1.5 times as long as mid-body diameter, consisting of a slender part with prismatic cells and a slightly wider pars dilatata; oviduct-uterus junction marked with a weak sphincter. Uterus simple tube, anterior 21–33 µm or 0.9–1.5 times and posterior 21–23 µm or 0.9–1.0 times as long as corresponding body diameter; sperms not observed. Vulva longitudinal. Vagina extending inwards about one-half (46–55%) of corresponding body diameter; pars proximalis vaginae longer than wide, 7–9 × 3 µm, with convex walls; pars refringens absent; pars distalis 2–3 µm with somewhat rounded walls. Prerectum 2.8–5.0 and rectum 0.7–1.3 times as long as anal body diameter. Tail elongate conoid, ventrally arcuate, with rounded terminus. Two caudal pores present on each side.

Male

Not found.

Taxonomic remarks

Dorylaimellus kasplateauensis sp. nov. comes close to D. andrassyi Heyns, 1963 in general morphology and measurements but differs in having a shorter body (L = 0.68–0.83 vs 0.87–2.3 mm), in the lip region morphology (lip region with weak perioral disc vs prominent perioral disc), in having a longer pharynx (b= 4.8–5.7 vs 5.7–12); and the absence of males (vs male present). It differs from the Kerala population of D. andrassyi (in the present paper), in having a shorter and robust body (L= 0.68–0.83 vs 1.0– 1.2 mm; a = 30–36 vs 44–53), in the lip region morphology (inner lips elevated forming a weak perioral disc vs prominent perioral disc), the longer and robust odontostyle (6–7 vs 4–5 µm long and slender), the longer pharynx (b= 4.8–5.7 vs 6.7–9.0), the larger expanded part of the pharynx (38–43 vs 24–35% of total neck length), as well as in the longer tail (c= 18–24 vs 26–32) and absence of males (vs present).

In the tail shape, the new species also comes close to D. basiri Jairajpuri, 1965 but differs in having a shorter and robust body (L= 0.68–0.83 vs 1.2–1.5 mm; a= 30–36 vs 48–54), in the lip region morphology (inner lips elevated forming a weak perioral disc vs absent), the longer odontostyle (6–7 vs 5 µm), the shorter odontophore with weakly developed basal flanges (1.6–2.3 times vs broadly flanges, about four times as long as odontostyle), the longer pharynx (b=4.8–5.7 vs 6.0–6.5), the shorter pharyngeal bulb (38–43% vs about one-half of total pharyngeal length), and the shorter prerectum (2.8–5.0 vs 7 times as long as anal body diameter).

Figures

Fig. 12. Dorylaimellus kasplateauensis sp. nov. A–C. Paratype 1, ♀ (slide 1). D, F. Paratype 2, ♀ (slide 1). E. Paratype 3, ♀ (slide 2). G–H. Paratype 5, ♀ (slide 4). A. Entire female. B. Anterior region. C. Anterior end showing amphid. D. Neck region. E. Female genital system. F. Vulva region. G–H. Female posterior region.

Fig. 13. Dorylaimellus kasplateauensis sp. nov. (LM photographs). A–C. Paratype 1, ♀ (slide 1). D–E, H–I. Paratype 2, ♀ (slide 1). F–G. Paratype 4, ♀ (slide 2). A–B. Anterior region. C. Anterior end showing amphid.D. Expanded part of pharynx.E. Vulva.F. Anterior genital branch.G. Posterior genital branch. H. Arrows indicating body pores. I. Female posterior end. Scale bars: A–I =10 µm.