Crassolabium dhritiae, Sen & Roy & Mandal, 2025

Sen, Debabrata, Roy, Samprit Deb & Mandal, Gurupada, 2025, A New Species of the Genus Crassolabium Yeates, 1967 (Nematoda: Dorylaimidae: Labronematinae) from India, Acta Zoologica Bulgarica 77 (1), pp. 13-22 : 14-18

Crassolabium dhritiae sp. n.

( Figs. 1 and 2 )

Measurements. See Table 1 . The measurements given hereafter are based on holotype. Minimummaximum ranges of measurements of paratypes are given in parentheses.

Female. Body moderately slender, mediumsized, ventrally curved, particularly in posterior portion when fixed, tapering towards anterior end. Cuticle in two layers, with fine transverse striations almost uniformly thick throughout the body except on tail, 2 μm (1.5–2.0 μm) thick at anterior end at the level of middle of the odontostyle, 3 μm (2–3 μm) at mid-body and 6 μm (5.0–5.5 μm) on tail. Lateral chords 1/4–1/3 of the body width near mid-body. Lip region round, amalgamated, labial and cephalic papillae not distinct, almost continuous or weakly set off by depression, narrower than adjoining body, 5 μm (4–5 μm) high and 14 μm (13–15 μm) or 0.8 (0.7–0.8) adjacent body-widths wide. Amphid fovea funnelshaped, its opening occupying 8 μm (6.5–8.0 μm) or about one-half of lip region width. Odontostyle 1.3 (1.2–1.4) lip region-widths long or 6.3 (6.3–6.6) times the width of odontostyle, thicker than cuticle at the same level, 3 μm wide; aperture occupying 6.5 μm (7.0–7.5 μm) or 34.2% (36.8–37.5%) of the odontostyle length. Guiding ring not much sclerotised, at 8 μm (8–9 μm) from anterior end. Odontophore simple, rod-like, 1.2 (1.1–1.2) times the odontostyle length. Nerve ring at 135 μm (128–161 μm) from anterior end or at 32.4% (29.2–34.6%) of pharynx. Cardia short, rounded to conoid, wide at pharyngointestinal junction and then narrow, 11 μm (8.5–11 μm) long. Pharynx long, gradually expands, slightly less than one-third or 28% (26.3–29.0%) of the body length. Expanded portion of pharynx slightly less than half of the pharyngeal length, 3.4 (3.7–4.2) times the neck base-width long or 42.7% (44.2–46.8%) of the pharyngeal length. Glandularium 157 μm or 88.2% (172–200 μm or 80.3–94.7%) of the expanded pharynx. Pharyngeal gland nuclei located as follows: D=62.2% (56.9–60.4%); AS 1 =52.2% (47.3– 57.0%); AS 2 =56.0% (53.7–58.1%); PS 1 =85.9% (75.5–81.9%); PS 2 =88.5% (80.02–88.3%). Female reproductive system didelphic-amphidelphic, with both genital branches equally well developed. Ovaries moderately large, posterior ovary longer than anterior ovary, reflexed (in one paratype reflexed up to sphincter); oocytes arranged in a single row except at the growth region. Anterior ovary 65 μm (63–68 μm) and posterior ovary 70 μm (63–101 μm) long. Oviduct long, tubular, joining the ovary sub-terminally, anterior oviduct 85 μm (95–101μm) and posterior oviduct 76 μm (84–95 μm) long. Indistinct sphincter present separating oviduct from uterus. Uterus muscular, short and simple, anterior uterus 92 μm (85–93 μm) and posterior uterus 104 μm (76–82 μm) long. Vulva transverse, equatorial, at 47–52.5% of the body. Two round gland cells present near vulva on both sides of vagina. Vagina extending inward about half or 55.5% (48.2–54.9%) of the corresponding body width. The length of pars proximalis vagina 20 μm (17–20 μm), pars refringens vaginae 7 μm (5–7 μm), sclerotised pieces almost triangular with concavity at the distal end, combined width of pars refringens vaginae 12 μm (10–12 μm); length of pars distalis vagina 3 μm in all specimens. Prerectum 2.2 (2.1–2.3) anal body widths or 2.4 (2.0–2.2) times the rectum length. Rectum 0.9 (1–1.1) anal body widths long. Tail short, ventrally straight and dorsally convex, conoid with rounded terminus, 0.9 (0.6–0.9) anal body-widths long. Caudal pores indistinct.

Male. Not found.

Juvenile (J4). Morphologically similar to females except smaller body, absence of female reproductive organs and differences in other measurements. Transverse cuticular striations very prominent, cuticle 2.0–2.5 μm thick at anterior end and at mid-body, 4–5 μm on tail. Lip region narrower than adjoining body, 4 μm high and 11–12 μm (or 0.7–0.8 adjacent body-widths wide). Amphids funnel shaped, 7 μm wide or about half of the corresponding body width. Functional odontostyle and replacing odontostyle same in length, 1.4–1.6 lip region-widths long, 2.5–3.0 μm wide, aperture occupying 6–7 μm or 35.2–38.8% of the odontostyle length. Guiding ring at 6.5–7.0 μm from anterior end. Odontophore 1.0–1.2 times the odontostyle length. Nerve ring at 111–117 μm from anterior end or at 31.5–36.6% of pharynx. Pharynx about one-third of body, 1/3.2–3.5 or 28.5–31.2% of the body length. Expanded portion of pharynx 3.7– 4.2 times the neck base-width long or 45.7–53.6% of the pharyngeal length. Prerectum 1.6–2.0 and rectum 0.90–0.95 anal body widths long. Tail short, convex both dorsally and ventrally, conoid with rounded terminus, 0.7–0.8 anal body-widths long.

Type habitat and locality. Collected from the forest ecosystem, soil around the roots of unidentified plant at Harichandrapur , Daldihi (21017 / 53 // N, 85050 / 46 // E), Keonjhar District, Odisha State, India .

Type specimens. Holotype along with three female paratypes, one juvenile on the same slide ( ZSI Holotype Registration Number WN 4814/1) and three female paratypes and one juvenile on another slide (ZSI Paratype Registration Number WN 4814/2-9 ) have been deposited in the National Zoological Collection , Zoological Survey of India, Kolkata, India.

Etymology. The new species has been named after Dr (Mrs) Dhriti Banerjee, Director, Zoological Survey of India.

Figures

Fig. 1. A–J. Crassolabium dhritiae sp. n., females.A.Anterior end showing odontostyle; B. Odontostyle; C. Pharyngointestinal junction; D. Entire body; E. Reproductive system; F. Vulva and vagina; G. Vulva and anterior gonad; H. tail. Juvenile. I. Anterior end showing odontostyle and replacing odontostyle; J. tail.

Fig. 2.A–L. Photomicrograph of Crassolabium dhritiae sp. n., females.A–I.Adult.A. Entire body. B. Odontostyle and amphid. C. Anterior end showing odontostyle. D. Pharynx. E. Posterior gonad. F. Anterior gonad. G. Reproductive system. H. Vulva and vagina. I. Posterior end showing tail. J–L. Juvenile. J. Entire body. K.Anterior end showing odontostyle. L. tail.