Willinema persicum, Vazifeh & Niknam & Jabbari & Fallahi & Zahedi & Peña-Santiago, 2022

Vazifeh, Nasir, Niknam, Gholamreza, Jabbari, Habibeh, Fallahi, Amin, Zahedi, Ebrahim & Peña-Santiago, Reyes, 2022, Description of Willinema persicum sp. n. (Dorylaimida: Thornenematidae) from Iran, with an updated taxonomy of the genus, Journal of Natural History 56 (13 - 16), pp. 849-863 : 851-858

Willinema persicum sp. nov.

( Figures 1–3 ; Tables 1 , 2 )

Diagnosis

The new species is characterised by its 1.42–1.89 mm long body, lip region offset by weak constriction and 10–13 μm broad, labial and post-labial sclerotisation absent, odontostyle 14–18 μm long, neck 270–306 μm long, pharyngeal expansion 110– 137 μm long and occupying 40–42% of total neck length, female genital system mono-opisthodelphic, anterior genital branch reduced to a uterine sac 41–133 μm long or 0.8–2.9 times the corresponding body diameter, posterior uterus tripartite, vulva a pre-equatorial (V = 39–44) transverse slit, tail short and convex-conoid to rounded (19–27 μm, c = 61–84, c ′ = 0.7–1.0), spicules 36–41 μm long, and 7–9 ventromedian supplements with hiatus.

Etymology

The specific epithet refers to Persia, the former name of Iran. Type locality and habitat

North-west Iran, East Azarbaijan province, Sufiyan, Roodghat area ( GPS (Global Positioning System) coordinates: 38.256°N, 46.159°E, altitude 1547 m a.s.l.), in the rhizosphere of common wheat ( Triticum aestivum L.) .

Other locality and habitat

North-west Iran, East Azarbaijan province, Arasbaran forests.

Material examined

9 ♀♀ and 6 ♂♂ from two locations and habitats, in acceptable condition.

Type material

♀ holotype, ♀♀ and ♂♂ paratypes deposited in the Nematology Collection of the Department of Plant Protection , Faculty of Agriculture , University of Tabriz , Tabriz , Iran, and one paratype ♀ (catalogue number = 682) and one paratype ♂ (catalogue number = 683) deposited in the Nematode Collection of the University of Jaén, Spain .

Description

Adult. Moderately slender nematodes (a = 30–39) of medium size, 1.42–1.89 mm. Body mostly curved ventrad upon fixation, especially in posterior region, C- or G-shaped. Body cylindrical, visibly tapering towards the anterior end, less so towards the posterior end since the caudal region is short and rounded. Cuticle two-layered, 1.5–2.5 μm thick in anterior region, 2–4 μm at mid-body and 5–7 μm on tail, outer layer distinctly thinner than the inner one and bearing fine transverse striation. Lateral chord very narrow, 3–6 μm wide or 6–15% of the corresponding body diameter. Lip region rounded, offset by a weak but perceptible constriction, 2.0–2.5 times as broad as high or one-fifth to one-third (21– 34%) of body diameter at neck base; lips rather amalgamate, with low papillae; labial and post-labial sclerotisation absent. Amphidial fovea stirrup-shaped, their aperture 5.5–7 μm wide, occupying 52–64% lip region diameter. Cheilostom a truncate cone, lacking any differentiation. Odontostyle dorylaimoid, typical of the genus, 1.2–1.5 times the lip region diameter and 1.0–1.1% of body length, with aperture 4.5–6 μm long or occupying 30–38% of its length. Guiding ring simple, located at 7–10 μm from the anterior end or 0.6–0.8 times the lip region diameter. Odontophore well demarcated, simple, rod-like, 1.1–1.2 times the odontostyle length. Nerve ring encircling the anterior slender part of pharynx, at 113–125 μm or 36–46% of neck length from anterior end. Anterior region of pharynx enlarging gradually, basal expansion 4.8–6.5 times as long as wide, 2.5–3.2 times as long as body diameter at neck base and occupying 40–42% of total neck length; gland nuclei located as follows: DN = 63–65, S1N1 = 69–73, S1N2 = 76–79, S2N = 83–86. Cardia conical, 15–22 × 7–11 μm, with a ring-like structure surrounding its junction to pharyngeal base.

Female. Reproductive system mono-opistho-ovarian. Anterior branch reduced to a simple uterine sac 41–133 μm long or 0.8–2.9 times the corresponding body diameter, empty, occupying 2.2–9.3% of body length. Posterior branch well developed, very variable in length, 278–407 μm or 15–28% of body length: ovary reflexed, not reaching the oviduct-uterus junction, measuring 50–75 μm, with oocytes arranged first in several rows and then in a single row; oviduct joining the ovary subterminally, 120–145 μm long, 2.4– 3.3 body diameter, and consisting of a tubular part and a poorly developed pars dilatata with distinct lumen; oviduct and uterus separated by a marked sphincter; uterus very long and tripartite, 170–236 μm or 3.4–5.4 body diameters, consisting of a proximal region with visible lumen, an intermediate muscular section with narrow lumen, and nearly spherical pars dilatata close to sphincter; sperm cells present in proximal uterine region. Vagina perpendicular to body axis, extending inwards 18–22 μm, up to one-half (36–51%) of body diameter: pars proximalis 11–15 × 11–14 μm, encircled by circular muscles, pars refringens consisting of two sclerotised triangular to drop-shaped pieces, each measuring 3.3–4.5 × 4.5 μm, and very short pars distalis. Vulva a pre-equatorial transverse slit. Prerectum 2.6–3.9, rectum 0.9–1.5 anal body diameters long. Caudal region short, convex conoid to rounded, with two pairs of caudal pores.

Male. Prerectum 4.1–5.0, cloaca 1.5–1.7 times the body diameter at level of cloacal aperture. Genital system diorchic, with opposed testes. In addition to the ad-cloacal pair, situated at 7–8 μm from the cloacal aperture, there is a series of 7–9 closely and irregularly spaced (9–14 μm apart) ventromedian supplements located outside the range of spicules. Spicules dorylaimoid, robust, sclerotised, 3.6–5.1 times as long as wide and 1.2–1.7 times the cloacal body diameter; head small, not offset, 3–5 μm long, occupying 7–14% of total spicule length, with its dorsal side slightly longer than the ventral one and slightly curved, ventral hump and hollow poorly demarcated but appreciable; median piece 24–26 μm long, occupying 48–50% of spicule length, and reaching the spicule posterior terminus. Lateral guiding piece small, 3–6 μm long. Caudal region similar to that of female.

Juveniles were not found.

Relationships

In having comparatively large general size (body 1.42–1.89 mm long, neck more than 270 µm long), short tail (c = 61–84) and 7–9 ventromedian supplements, the new species is easily distinguishable from other members of the genus. It resembles W. eburnense and E. paraparvum , two African ( Ivory Coast and Cameroon, respectively) species, in the presence of a reduced (but appreciably long, more than 40 µm) anterior genital branch, differing from these two species in its longer odontostyle (14–18 vs up to 14 µm), and more anterior vulva (V = 39–44 vs V = 48–51 and V = 44–48, respectively). There are also differences in c values in both males (c = 61–80 vs 38–40 and 48–57, respectively) and females (c = 62–84 vs 38–44 and 48–57, respectively).

Willinema persicum sp. nov. differs from W. eburnense mainly in longer pharyngeal basal expansion (115-127 vs 90–98 µm and 110–137 vs 92–93 µm, respectively) in the females and males, greater body width at mid-body (43–50 vs 34–37 µm, 41–45 vs 29–34 µm, respectively) in both females and males, and relatively longer spicule (36–41 vs 29–35 µm) and prerectum (64–95 vs 43–49 µm, 103–115 vs 45–61 µm, respectively) in females and males. The new species can be differentiated from W. paraparvum by higher odontostyle length in females and males (15–17 vs 12–12.5 µm, 14–18 vs 12.5 µm, respectively), prerectum length (64–95 vs 46–51 µm, 103–115 vs 74–87 µm, respectively), body width at neck base (38–45 vs 28–31 µm, 37–45 vs 33–35 µm, respectively) and mid-body (43–50 vs 29–32 µm, 41–45 vs 34.5–36.5 µm, respectively).

Figures

Figure 1. Willinema persicum sp. nov. a.. ♀, neck region. b.♀, anterior region in lateral surface view. c. ♂, entire. d. ♀, anterior body region in lateral median view. e. ♀, genital system. f. ♂, posterior body region. g. ♀, entire. h. Spicules. i. Lateral guiding pieces. j. ♀, posterior body region.

Figure 2. Willinema persicum sp. nov. (♀, LM). a, b. Anterior body region in lateral median view. c. Pharyngeal expansion and pharyngo-intestinal junction. d. Anterior end in lateral surface view. e. Genital system. f. Vagina and anterior uterine sac. g. Posterior body end. h. Entire. Scale bars: A– G = 10 μm; H = 100 μm.

Figure 3. Willinema persicum sp. nov. (♂, LM). a. Anterior body region in lateral median view. b. Entire. c. Pharyngeal expansion and pharyngo-intestinal junction. d. Spicules. e. Posterior body region. Scale bars: A, C–E = 10 μm; B = 100 μm.