Ditylenchus paraparvus, Hashemi & Karegar, 2019

Hashemi, Kobra & Karegar, Akbar, 2019, Description of Ditylenchus paraparvus n. sp. from Iran with an updated list of Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae), Zootaxa 4651 (1), pp. 85-113 : 87-90

Ditylenchus paraparvus n. sp.

( Figures 1 & 2 )

Measurments: table 1.

Female: body short, slightly ventrally arcuate when relaxed. Cuticular annulation distinct, 1–2 µm wide; lateral fields with four incisures, 2–6 µm wide, occupying 18.3–40.7% of body width. Head low, 1.5–2 µm high and 4–5 µm wide, not offset, with two or three fine annuli. Cephalic skeleton weak, outer margins of basal plates extended two annuli inside body. Stylet delicate, conus 34.3–47.7% of stylet length, knobs small and rounded or sloping backwards, 1–1.5 µm wide, sometimes asymmetrical. DGO 1–1.5 µm posterior to stylet knobs. Median bulb oval, 4–5.5 µm wide, muscular, with thickening of lumen wall about 1–1.5 µm long. Isthmus cylindrical and more slender than procorpus. Nerve ring surrounding isthmus in anterior half to almost its middle, 58.4 (54–62) µm from anterior end. S-E pore located from posterior half of isthmus to anterior half of basal pharyngeal bulb. Hemizonid about two cuticular annuli long, 71.9 (66–74.5) µm from the anterior end, immediately or one annulus anterior to the S-E pore. Deirids at level of S-E pore. Basal pharyngeal bulb pyriform and offset from intestine, the ratio of its length to width is 2.5 (2.1–4.0), with the two most anterior intestinal cells appearing hyaline. Ovary outstretched, oocytes in single row, spermatheca elongate and filled with rounded sperms, uterus quadricolumellar, vagina 4.5-6.5 µm and 34.1–51.6% of VBW. PUS 5–10 µm long, 0.6 (0.4–0.8) times VBW or 14.2 (7.0–20.2) % V-A distance. Post-vulval body length 14.5 (11.9–16.6) times ABW. Tail almost cylindrical and sometimes tapering gradually from anus, with rounded terminus, only one specimen with small mucron.

Male: Similar to female in general body characteristics, but slightly narrower and in one specimen with a short basal pharyngeal bulb overlap over the intestine (about 2 µm). Spicules slightly ventrally arcuate, gubernaculum simple and crescent-shaped. Bursa with crenate margin, 13–22 µm long and enveloping 27.4–40.1% of tail length.

Habitat & locality. This population was found in soil around vegetable roots, in a suburb of Kezerun, Fars province, Iran.

Type material. Holotype female, five paratype females and four paratype males kept in the nematode collection of the Department of Plant Protection , School of Agriculture, Shiraz University, Iran, and three female paratypes and three paratype males on two slides deposited in the Nematode Collection of the Plantenziektenkundige Dienst , Wageningen , The Netherlands .

Diagnosis and relationships. Ditylenchus paraparvus n. sp. is characterised by a short body length (441–543 µm), four incisures in lateral fields, delicate and short stylet (6–7.5 µm) with small rounded or sloping backwards knobs, pyriform and offset basal pharyngeal bulb, V = 67.7–76.4, short PUS (5–10 µm), less than one VBW in length, small spicules (12.5–15 µm) and almost cylindrical tail (71–90 µm) with rounded terminus. D. paraparvus n. sp. resembles D. gallaeformans Oliveira, Santin, Seni, Dietrich, Salazar, Subbotin, Mundo-Ocampo, Goldenberg & Barreto, 2013 , D. longimatricalis ( Kazachenko, 1975) Brzeski, 1984 , D. parvus Zell, 1988 , and D. terricolus Brzeski, 1991 . It differs from all of these species by shorter PUS and smaller PUS/ VBW ratio (0.4–0.8 vs. 1.4–1.8, 1.8–5.1, 1.8–4.3 and 2.1–3.2, respectively). In addition, D. gallaeformans has longer spicules (16.5–26 vs. 12.5–15 µm), bursa reaching the tail tip (vs. covering 27.6–40.1 % of tail in D. paraparvus n. sp.) and has a more conical tail with pointed to minutely rounded tip (vs. almost cylindrical with rounded tip); D. parvus has greater c ratio (8.6–15.0 vs. 5.4–6.2); while D. terricolus has greater c (9.1–12.1 vs. 5.4–6.2) and smaller c′ (4.5–7.1 vs. 7.6–9.4) ratios.

Etymology. The specific epithet is derived from the Greek ‘ para ’, which means beside, near, and ‘ parvus’. It refers to the similarity of this species to D. parvus .

Figures

FIGURE 1. Ditylenchus paraparvus n. sp. C–H, J & K: Female. A, B, I, L & M: Male. A & F: General shape; B–D: Head & stylet; E: Pharynx; G: Post-vulval uterine sac; H & I: Basal pharyngeal bulb; J: Lateral fields; K & L: Tail; M: Spicules.

FIGURE 2. Ditylenchus paraparvus n. sp. A–G & I: Female. H: Male.A & B: Head & stylet; C: Lateral fields; D: Median bulb; E & F: Basal pharyngeal bulb; G: Post-vulval uterine sac; H: Spicules; I: Tail (Scale bars = 10 µm).