Allodorylaimus kazirangus, Baniyamuddin & Ahmad, 2011

Baniyamuddin, Md. & Ahmad, Wasim, 2011, Two new and a known species of dorylaim nematodes (Dorylaimida: Nematoda) from Kaziranga National Park, Assam, India, Journal of Natural History 45 (47 - 48), pp. 2965-2980 : 2970-2975

Allodorylaimus kazirangus sp. nov.

( Figures 3 and 4 ; Table 2)

Description

Female. Body slightly curved ventrad upon fixation, tapering towards both extremities. Cuticle finely striated, 2–3 µm at mid-body and 3–4 µm on ventral side of tail just posterior to anus. Lateral chords about one-fifth of corresponding body width wide. Lateral body pores indistinct, ventral body pores 9–11 in pharyngeal region, 4–6 between pharynx base to vulva and 4–6 between vulva and anus; dorsal pores numbering 3 located anterior to nerve ring. Lip region truncate, slightly offset by constriction, about three times as wide as high and one-third as wide as body width at neck base; lips moderately fused with round contour. Amphids stirrup-shaped, fovea duplex, its aperture wide, slit-like occupying about two-thirds of the corresponding body width. Odontostyle 1.3–1.5 times lip region width long, its aperture about one-third of its length. Guiding ring single, fixed ring at 0.51–0.54 lip region width from anterior end. Odontophore simple, rod-like, 1.40–1.46 times as long as the odontostyle. Nerve ring at 32–33% of neck length from anterior end. Pharyngeal expansion gradual; expanded portion occupying about 52–55% of total neck length. Cardia short conoid; an asymmetrical ring-like structure surrounds the junction between pharyngeal base and cardia. An elongate subdorsal glandular mass (pseudocoelomocyte) present just posterior to pharyngo-intestinal junction. Pharyngeal gland nuclei located as follows: D, 46–49; AS 1, 15–18; AS 2, 35–38; PS1, 72–74; PS2, 75–77. Genital system amphidelphic; both the sexual branches almost equally developed. Ovaries reflexed, measuring 105–190 µm (anterior) and 103–164 µm (posterior); with oocytes arranged in a single row except near tip. Oviduct measuring 70–95 µm (anterior) and 80–95 µm (posterior), consisting of a proximal pars dilatata with distinct lumen and a distal slender portion with prismatic cells joining ovary subterminally. Sphincter present at oviduct–uterus junction. Uterus a characteristically long, tripartite tube with wide proximal portion followed by a long narrow intermediate portion with moderately sclerotized inner lining, joining a wider pars dilatata distalis; measuring 202–248 µm (anterior) and 207–300 µm (posterior). Vagina about two-fifths of the corresponding body width deep. Pars proximalis vaginae 20–21 µm long with straight walls encircled by circular musculature; pars refringens vaginae with triangular sclerotization, each measuring 7–8 by 4.5–5 µm, cw 11.5–12 µm; pars distalis vaginae 4.5–5.0 µm with curved wall. Vulva transverse. Pre-rectum 2.1–2.3 anal body widths long. Rectum 1.3 anal body widths long. Tail short conoid, generally bent ventrally, 1.02–1.21 anal body width long, with three caudal pores on each side.

Male. Similar to female in general morphology, except for being more ventrally curved in posterior region because of the presence of copulatory muscles. Supplements, an adcloacal pair and 13–14 regularly spaced ventromedians, which lack hiatus; ad-cloacal pair at 12–13 µm from the cloacal aperture, first ventromedian at 13 µm and 18 µm from the ad-cloacal pair while the second one at 17 µm and 9 µm, respectively, in the two males observed, rest of the ventromedians almost at regular intervals. Spicules dorylaimoid, 1.64–1.69 times anal body width long. Lateral guiding pieces rod-like, about one-quarter of spicules length. Pre-rectum 3.7–4.2 anal body widths long, terminating within the range of supplements at level with seventh to eighth supplement and ninth to tenth supplements, respectively. Tail short conoid, ventrally arcuate, 1.1–1.2 times anal body width long, with one subventral and two subdorsal coudal pores on each side.

Type habitat and locality

Soil around the roots of forest trees from tropical semi-evergreen forest area, Kaziranga National Park, Assam, India

Type specimens

Holotype female on slide Allodorylaimus kazirangus sp. nov. / 1; paratype females and males on slides Allodorylaimus kazirangus sp. nov. / 2; deposited with the nematode collection of the Department of Zoology Aligarh Muslim University, Aligarh.

Diagnosis and relationships

Allodorylaimus kazirangus sp. nov. is characterized by having body 1.84–2.16 mm long; slightly offset, truncate lip region; 30 µm long odontostyle; duplex amphid with wide aperture; cardia short conoid, an asymmetrical ring-like structure surrounds the junction between pharyngeal base and cardia; vulva a transverse slit; uterus characteristically long, tripartite with wide proximal portion followed by a long narrower intermediate portion with moderately sclerotized inner lining, joining a wider pars dilatata distalis; tail short conoid, similar in sexes and males with 13 to 14 regularly spaced ventromedian supplements and pre-rectum terminating within the range of supplements.

With its offset lip region, long odontostyle and number and arrangement of ventromedian supplements, the new species is similar to Allodorylaimus holdemani ( Andrássy, 1959) Andrássy, 1986 ; Allodorylaimus uniformis ( Thorne & Swanger, 1936) Andrássy, 1986 and Allodorylaimus paragranuliferus Quijano et al., 1991 . However, it differs from A. holdemani by the shape of the lip region (versus lip region offset by deep constriction, lips distinctly separate with angular contour), the amphid duplex (versus amphid simple); the longer odontostyle (versus odontostyle 27–28 µm), the shorter and differently shaped tail (versus tail slightly dorsally concave, conical and pointed), and the shorter spicules (versus spicules 72 µm).

From A. uniformis , the new species differs by the nature of its lip region (versus offset by depression); the amphid duplex (versus amphid simple); longer odontostyle (versus odontostyle 1.2 lip region width long); the shorter tail (versus c = 25, c’ = 2 in females; c = 31, cl = 1.8 in males), shorter spicules (versus spicules 2.4 anal body widths long), and in the arrangement of ventromedian supplements (one or two versus four supplements within the range of spicules).

From A. paragranuliferus , the new species differs by the shape of the lip region (versus lip region markedly set off with angular lips); its wider and duplex amphid (versus simple, 7.7–12 µm wide aperture); the longer odontostyle (versus odontostyle 16–25.5 µm); in the structure of its uterus (versus uterus a simple tube), and in the arrangement of ventromedian supplements in males (contiguous ventromedians with no pre-cloacal space versus only one supplement within the range of spicules and is clearly separated from the others).

The new species also resembles A. septentrionalis ( Kreis, 1963) Andrássy, 1986 in its tail shape but distinctly differs from the latter in having a longer odontostyle (versus 17–19 µm), a transverse vulva (versus longitudinal); differently shaped pars refringens vaginae (versus pars refringens vaginae rhomboid in shape), comparatively longer pre-rectum (versus 1.4–1.8 anal body widths long) and comparatively shorter spicules (versus spicules 62–68 µm). In A. septentrionalis , the tail is more sharply pointed with strong ventral curvature near its tip.

Figures

Figure 3. Allodorylaimus kazirangus sp. nov. (A) Anterior region, (B) anterior end showing amphid, (C) pharyngeal expansion, (D) anterior genital branch, (E) vulval region, (F) female posterior region, (G) female posterior end, (G) male posterior region, (H) male posterior end.

Figure 4. Allodorylaimus kazirangus sp. nov. (A–D) Anterior region, (E) pharyngo–intestinal junction, (F) vulval region, (G) female genital branch showing uterus, (H,I) female posterior end, (J) male posterior region. Scale bars: A–C,E,F,H,I = 10 µm; D,G,J = 20 µm).