Dorella shamimi, Ahmad, Wasim, 2010

Ahmad, Wasim, 2010, Three new and a known species of Tylencholaimoidea (Nematoda: Dorylaimida) from Singapore, Zootaxa 2505, pp. 51-64 : 56-59

Dorella shamimi n. sp.

( Figs. 3 , 4 )

Measurements: Table 1 .

Description. Female: Body slightly curved ventrad upon fixation, tapering slightly towards both extremities. Outer cuticle very finely striated, striations distinct in the posterior half of body; inner layer distinctly transversely striated, loose, 1.0–1.5 µm thick at mid body and 1.5–2.0 µm on tail, radial refractive elements abundant. Lateral hypodermal chords wide, about two-thirds of body width at mid body. Lateral, dorsal and ventral body pores indistinct.

Lip region continuous, rounded, smooth, about two-fifths as wide as body width at neck base; lips amalgamated; labial papillae indistinct; labial disc absent. Amphids cup-shaped, aperture width about threefourths of the lip region width; fusus at 10–11 µm behind amphid aperture, at level with the ventral stiffening piece of odontostyle. Odontostyle cylindroid, about 1.3–1.6 times lip region width long; its aperture about one-sixth of if its length; a large pad-like muscular structure attached on ventral side (ventral stiffening piece) of posterior half of the odontostyle extending to the anterior part of odontophore. Odontophore short, asymmetrical, 0.3–0.4 times or about one-third of the odontostyle length long with one ventral and two subdorsal, round, transparent, knob-like thickenings. Guiding ring single, fixed ring at 0.6–0.7 times the lip region width from anterior end. Nerve ring at 46–49% of neck length from anterior end. Pharynx a cylindrical tube with a terminal oval bulb offset from anterior part, measuring 23.5–25.5 x 9–10 µm or about 17–19% of the total neck length; the two parts of pharynx separated by a distinct constriction. Cardia short-conoid.

Genital system monodelphic-prodelphic. Posterior branch represented by a small uterine sac, about 0.4– 0.9 times the corresponding body width long. Ovary reflexed, measuring 110–142 µm with oocytes arranged in a single row except near tip. Oviduct joining ovary subterminally, measuring 75–111 µm in length. Sphincter indistinct at oviduct-uterus junction, only a slight demarcation of the two parts visible. Uterus an undifferentiated tube, 45–85 µm in length. Vagina thick walled, sigmoid, about half of corresponding body width deep; pars proximalis vaginae 5–5.5 µm long with convex walls, encircled by circular musculature; pars refringens vaginae absent; pars distalis vaginae 1.5–2 µm long with curved wall. Vulva tranverse, slitlike. Prerectum 3.5–5.1 anal body widths in length. Rectum about one anal body width long. Tail short conoid, with rounded terminus, length about 1.3–1.6 times anal body width. Caudal pores two on each side

Male: Supplements an adcloacal pair and a single well developed ventromedian at 32–34 µm from the adcloacal pair. Spicules slightly arcuate, 1.5 anal body widths long; lateral guiding pieces about one-fifth of spicule length. Prerectum about 5 times the anal body width in length, extending far beyond the range of supplements. Rectum length 1.5 times anal body width. Tail short, conoid, 1.5–1.7 anal body widths long. Caudal pores two on each side.

Type habitat and locality: Soil around roots of forest trees from near the visitor centre, Sungei Buloh Wetland Reserve, Singapore; collected on 26 August 2003.

Type material: Holotype female on slide Dorella shamimi n. sp. /1; paratype females and males on slide Dorella shamimi n. sp. / 2–5; deposited with nematode collection of the Department of Zoology, Aligarh Muslim University, India.

Diagnosis and relationships: Dorella shamimi n. sp. is charaterised by having 0.58–0.62 mm long body; continuous lip region with indistinct labial papillae; labial disc absent; 10–10.5 µm long odontostyle with a large pad-like muscular structure attached on ventral side of posterior half of its length extending to the anterior part of the odontophore; odontophore asymmetrical with round, transparent, knob-like thickening; pharynx with a short terminal oval bulb; mono-prodelphic female genital system with a short post-uterine sac; short conoid tail, with rounded terminus, and males with 18–18.5 µm long, simple arcuate spicules and a single ventromedian supplement.

In the presence of a continuous lip region and absence of labial disc, the new species closely resembles D. abrupta Siddiqi, 1995 but differs from it in having comparatively slender body (vs a= 24.7–25.3); longer odontostyle (vs odontostyle 7.0–7.5 µm long); shorter odontophore (vs odontophore 4.5–5.0 µm long or about two-thirds of odontostyle length); comparatively larger pharyngeal bulb (vs 20 x 12.5 µm); posterior vulva position (vs V= 60.9–62.8); shorter post-uterine sac (vs 1.0–1.5 times corresponding body width long); longer prerectum (vs 1.8 times anal body width long), and slightly longer spicules (vs 17 µm).

D. shamimi n. sp. closely resembles D. annulata Siddiqi, 1995 in its tail shape but differs in having less prominent body annulations (vs cuticle distinctly annulated), in having continuous lip region (vs lip region offset by expansion); in the absence of labial disc (vs labial disc present); longer prerectum (vs prerectum two anal body widths long); comparatively shorter tail (vs tail 1.7–1.9 times anal body width long), and in the absence of males.

Etymology: The species epithet shamimi refers to Prof. M. Shamim Jairajpuri, a world authority on nematode taxonomy.

Figures

FIGURE 3. Dorella shamim i n. sp. A: Entire female. B: Entire male. C: Anterior region. D: Anterior end showing amphid. E: Pharyngeal region. F: Female genital system. G: Female posterior region. H: Male posterior region.

FIGURE 4. Dorella shamimi n. sp. A-B: Anterior region. C: Anterior region showing amphid. D: Expanded part of pharynx. E: Vulva region. F: Female posterior region. G: Male posterior region. (scale bar = 10 um)