Eudorylaimus meridionalis Tjepkema, Ferris & Ferris 1971

Eudorylaimus meridionalis Tjepkema, Ferris & Ferris, 1971 Fig. 2, Table 1 Eudorylaimus meridionalis Tjepkema, Ferris & Ferris, 1971: 23 (original description). Type specimens. Holotype • Indiana (slide no. 4 / 3 / 68 E 8) – Pardue Nematode Collection, grassy area, Brown County State Park; Paratypes • same data as holotype (slide no. 7 / 22 / 67 C 10 / 2 ♀, 4 / 5 / 68 C 19 / 1 ♀, 5 / 31 / 68 B 4 / 1 ♀, 8 / 14 / 68 H 7 / 1 ♀, 4 / 2 / 68 F 1 / 1 ♀, 4 / 1 / 67 A 1 / 2 ♀, 4 / 4 / 68 N (2) 4 / 3 ♀, 10 / 13 / 68 A 15 / 1 ♀), 4 / 4 / 68 N (3) 1 / 1 ♀, 4 / 3 / 68 EB / 2 ♀). Not examined. Material examined. China • 2 ♀ (IAE / NC / EU / E. meridionalis / 1), Liaoning Province, Panjin City, Dawa; 41.037108°N, 121.948279°E; soil samples collected from around the roots of grasses (unidentified) • 3 ♀ (IAE / NC / EU / E. meridionalis / 2–3), Liaoning Province, Huludao City, Xingcheng; 40.860423°N, 120.95638°E; soil samples collected from around the roots of grasses (unidentified) • 2 ♀ (IAE / NC / EU / E. meridionalis / 4), Liaoning Province, Jinzhou City, Linghai; 40.974492°N, 121.101014°E; soil samples collected from around the roots of grasses (unidentified). Description. Female. Slender nematodes of medium-size, 0.9–1.1 mm long body; curved ventrally or open C-shaped upon fixation. Body cylindrical, tapering gradually towards both extremities but more so towards the posterior region. Cuticle with two distinct layers, 1.5–2.5 μm thick at the anterior region, 2.0–3.0 μm at midbody, and 3.0–4.0 μm on tail. Outer cuticle smooth or finely striated, inner layer with fine transverse striations. Lateral, dorsal, and ventral body pores indistinct. Lateral chords 10–14 μm wide at midbody, occupying ~ 1 / 3 (29–37 %) of the corresponding body diameter. Lip region offset from the body by constriction, 2.5–2.8 times as wide as high or 1 / 3 to 2 / 5 (36–43 %) of the body diameter at the pharyngeal base. Lips smaller, slightly angular and separated; labial papillae raised from labial contour. Amphidial fovea stirrup-shaped, aperture slit-like, 6.0–7.5 μm wide or occupying 1 / 2 (46–53 %) of lip region diameter. Cheilostom a truncate cone. Odontostyle typical dorylaimoid, 5.2–6.0 times as long as wide, 0.82–1.1 times the lip region diameter long or 1.0–1.5 % of total body length, its aperture 4.5–6.0 μm or 1 / 3 to 2 / 5 (33–40 %) of its length. Odontophore linear, rod-like, 1.3–1.9 times the odontostyle length. Guiding ring simple, at 0.50–0.57 times the lip region diameter from anterior end. Pharynx consisting of a weakly muscular anterior part, expanding gradually into a cylindroid part, occupying ~ 38–42 % of the total pharyngeal length; expanded part of the pharynx 5.0–6.2 times as long as wide, 2.8–3.3 times body diameter at neck base. Pharyngeal gland nuclei and their orifices are located as follows: DO = 65.1–67.1, DN = 69.5–71.5, DO – DN = 3.6–5.7, S 1 N 1 = 77.2–79.6, S 1 N 2 = 81.0–83.9, S 2 N = 90.8–92.8, S 2 O = 91–93. Nerve ring encircling the pharynx at 38–42 % of the neck length from the anterior end. Cardia rounded to conoid, ~ 1 / 2 (44–58 %) of the corresponding body diameter long, with a well-developed cardiac disc. Genital system didelphic – amphidelphic; both the genital branches almost equally developed. Anterior genital branch 7.6–13.6 % and the posterior genital branch 9.2–12.3 % of the body length. Ovary reflexed, not reaching the oviduct-uterus junction; measuring 45–68 μm or 1.0–2.0 (anterior) and 49–79 μm or 1.1–2.0 (posterior) times the corresponding body diameter long; oocytes arranged in a single row except near the tip. Oviduct joining the ovary sub-terminally, measuring 43–60 μm or 1.1–1.7 (anterior) and 42–66 μm or 1.2–1.6 (posterior) times the corresponding body diameter long; consisting of a slender distal portion and a well-developed pars dilatata. Oviduct-uterus junction marked by a well-developed sphincter. Uterus short, tubular, measuring 31–53 μm or 0.72–1.3 (anterior) and 33–48 μm or 0.88–1.2 (posterior) times the corresponding body diameter long, bipartite, a well-developed muscular proximal part, and a short, slender distal part. Vagina extending inwards, 14–18 μm or ~ 2 / 5 to 1 / 2 (39–45 %) midbody diameter; pars proximalis 8–11 × 8.0–10.5 μm, with somewhat sigmoid wall encircled by circular muscles; pars refringens with two small trapezoid-shaped sclerotized pieces, measuring 5–7 × 2–3 μm and the combined width 7–9 μm; pars distalis 1.5–2.0 μm. Vulva a transverse slit. Sperm cells absent. Prerectum 1.2–2.4 and rectum 1.0–1.3 times the anal body diameter long. Tail long, conoid, ventrally arcuate with rounded to subacute tip, 1.8–2.3 times anal body diameter long; hyaline part of tail always perceptible, ~ 1 / 5 to 1 / 3 anal body diameter long with a pair of caudal (Fig. 2 L) pores on dorsal side. Male. Not found. Remarks. Tjepkema et al. (1971) described this species from several localities of Indiana, USA. In the present study, we have recorded this species from several localities of Liaoning Province in China. The present populations are similar to the type population, except that slight morphological and morphometrics variations are observed: odontophore distinct, 1.3–1.9 times odontostyle length (vs odontophore length obscure); comparatively longer cardia (17–21 vs 8–17 μm) and shorter rectum (24–31 vs 45 μm). In the presence of long conoid tail, E. meridionalis resembles E. aquilonarius Tjepkema et al., 1971 but differs in having comparatively shorter odontostyle (11.5–15 vs 16 μm); differently shaped amphidial aperture (stirrup-shaped vs beaker-shaped) and pars refringens (trapezoidal vs triangular shaped) and shorter prerectum (27–56 vs 59 μm). This species is recorded here for the first time from China.