Ditylenchus valveus Thorne & Malek 1968

10. Ditylenchus valveus Thorne & Malek, 1968

9 females: L = 739 (638–907) µm; stylet = 7.2 (7–8) µm; pharynx = 123 (106–153) µm; tail = 66.4 (55–92) µm; a = 38.3 (29.3–51.7); b = 6.1 (5.2–8.0); c = 11.5 (9.8–14.4); c′ = 5.5 (4.5–7.4); V = 80.4 (79.0–82.7); V′ = 88.3 (84.9–89.8); PUS/VBW = 2.0 (1.1–2.6); PUS/V-A = 46.2 (23.5–68.4) %; V-A/T = 1.2 (1.0–1.8).

2 males: L = 625, 816 µm; stylet = 7, 8 µm; pharynx = 122, 128 µm; tail = 59, 74 µm; a = 44.5, 54.1; b = 5.1, 6.4; c = 10.5, 11.1; c′ = 5.4, 6.3; spicules = 18.5, 19 µm.

Diagnosis. D. valveus is characterised by six lateral field incisures, delicate, short stylet with round knobs, usually pyriform, but sometimes cylindrical, basal pharyngeal bulb that is usually offset and sometimes with slight overlap (up to 2 µm), posterior position of vulva, usually long post-vulval uterine sac, usually dull and rounded, but sometimes mucronate, tail tip, and spicule length.

The Iranian population of D. valveus comes close to D. acutatus, D. apus, D. dauniae, D. elegans, D. geraerti, D. medicaginis, D. myceliophagus, D. silvaticus, D. tenuidens and D. triformis. It can be distinguished from D. acutatus by its lower PUS/VBW ratio (1.1–2.6 vs. 2.8–4.1) and different tail tip (rounded to dull vs. pointed), from D. apus by having greater V and PUS/VBW ratio (79.0–82.7 and 1.1–2.6 vs. 75–76 and 0.2–0.4, respectively) and also by the shape of the basal pharyngeal bulb (pyriform and usually offset vs. elongate with long overlap), from D. dauniae by lower V (79.0–82.7 vs. 83–84) and greater c ′ index (4.5–7.4 vs. 3.2–4.1), from D. elegans by shorter body and tail length (638–907 and 55–92 vs. 1030–1370 and 111–149 µm), greater V (79.0–82.7 vs. 71–77), lower c ′ ratio (4.5–7.4 vs. 7.2–11.3) and different tail tip shape (rounded and dull vs. pointed), from D. geraerti by tail shape (narrow with rounded to dull tip vs. thick with rounded tip) and greater c′ index (4.5–7.4 vs. 3.5–5), from D. myceliophagus by different cephalic skeleton development (moderate vs. crescentic and refractive), from D. silvaticus by different tail shape (narrow with rounded to dull terminus vs. thick with pointed or rounded tip with mucron), from D. tenuidens by striated (vs. smooth) head, position of S-E pore (located between posterior half of isthmus and anterior half of basal bulb vs. half of isthmus), shape of basal bulb (pyriform vs. elongate) and tail tip (rounded to dull vs. pointed), and from D. triformis by longer spicules (18.5–19 vs. 13–15 μm) and having six incisures at anus region (vs. four). The closest species to D. valveus is D. medicaginis (see D. medicaginis diagnosis).