Nothotylenchus geraerti Kheiri, 1971

Hashemi, Kobra & Karegar, Akbar, 2020, New and known species of Nothotylenchus Thorne, 1941 (Nematoda: Anguinidae) from Iran with an updated list of species, Zootaxa 4729 (4), pp. 482-500 : 491

1. Nothotylenchus geraerti Kheiri, 1971

48 females: L = 742 ± 122 (506–1172) µm; stylet = 7.3 ± 0.3 (6.5–8) µm; pharynx = 127 ± 17 (96.5–167) µm; tail = 59.6 ± 8.1 (43.5–77) µm; a = 37.6 ± 4.9 (28.7–50.0); b = 5.8 ± 0.6 (4.6–7.6); c = 12.3 ± 1.4 (9.3–15.6); c′ = 4.9 ± 0.6 (3.7–6.1); V = 81.0 ± 2.3 (74.8–84.6); V′ = 88.3 ± 2.3 (82.0–95.8); PUS/VBW = 1.8 ± 0.4 (1.1–3.0); PUS/V-A = 42.9 ± 11.7 (14.8–77.0) %; V-A/T = 1.3 ± 0.2 (0.9–2.2).

10 males: L = 609 ± 75 (493–738) µm; stylet = 7.2 ± 0.2 (7–7.5) µm; pharynx = 122 ± 17 (98–154) µm; tail = 57.1 ± 7.5 (46.5–68.5) µm; a = 38.5 ± 2.6 (34.7–42.6); b = 4.9 ± 0.2 (4.6–5.3); c = 10.8 ± 1.6 (8.2–13.3); c′ = 5.0 ± 0.8 (4.1–6.3); spicules = 16.9 ± 1.1 (15.5–18.5) µm.

Diagnosis and relationships. Nothotylenchus geraerti is characterised by its medium-sized body, six lateral field incisures, delicate stylet with posteriorly-sloping knobs, pyriform or slightly elongate and offset or slightly overlapping basal pharyngeal bulb, posterior vulva position, medium-sized spicules, and variable tail terminus shape (rounded to pointed).

The studied populations of N. geraerti are similar to N. affinis , N. hexaglyphus , N. medians , N. taylori and N. tuberosus . The species differs from N. hexaglyphus by its more developed stylet and knobs, greater PUS/VBW ratio (1.1–3.0 vs. 0.5–1.1) and shorter spicules (15.5–18.5 vs. 19–22 μm). The four other species are very similar to N. geraerti , and, as their differentiation is so difficult, we think that these four species may all be synonymous. However, according to other published studies ( Kheiri 1971, Husain & Khan 1974, Brzeski 1991, Zeidan & Geraert 1991), N. geraerti differs from N. affinis by its shorter stylet (6.5–8 vs. 8–9 μm), higher head, and greater PUS/VBW average (˃1.5 vs. ˂1.5), from N. medians by higher head, posteriorly slopping knobs (vs. rounded) and less-thick tail (vs. thick), from N. taylori by its relatively shorter spicules (maximum length ˂ 19 vs. ˃ 19 μm), and from N. tuberosus by shorter uterus length/VBW ratio (˂ 3 vs. 3–4) and basal bulb shape (mostly pyriform and offset vs. slightly overlapping). All of the features used to differentiate these four species display inter-population variation, making further studies on their type specimens necessary.