Thelandros karkasensis sp. nov.

Figs. 5–7

General: Cylindrical worms with rounded cephalic extremities. Mouth subtriangular. Three cuticular flaps present just inside buccal cavity. Excretory pore located posterior to oesophageal bulb, lined by ring of relatively thick cuticle.

Male (based on holotype and 9 paratypes; mean ± SD [range]): Three cuticular flaps just inside buccal cavity. Body length 2.89 ± 0.62 mm (2.24–3.65 mm), width at level of excretory pore 168 ± 29 (137–225). Cuticlar annulations, approximately 10 µm wide at mid-body. Oesophageal corpus 768 ± 71 (690–907) long; isthmus 37 ± 6 (25–43); bulb 93 ± 10 (79–108) long, 102 ± 13 (77–124) wide. Nerve ring and excretory pore 172 ± 20 (138–205) and 1083 ± 123 (940–1253), from anterior end, respectively. Three pairs of caudal papillae: anterior pair ventrolateral, just anterior to cloaca, rod-shaped (Fig. 7 B, C); adcloacal pair flask-shaped, lateral (Fig. 7 B); third pair, small rod-shaped, well separated from each other (Fig. 7 A), 58 ± 7 (49–74) from tip of tail filament. Pre- and adcloacal papillae pedunculate. Caudal alae extend from base of adcloacal peduncle to posterior to last pair of caudal papillae. Anterior cloacal lip deeply divided into 4 sharply pointed lobes, some of which are further subdivided into 2 short lobes (Fig. 7 B); posterior cloacal lip bi-lobed. Spicule 69 ± 3 (64–76) long, straight, sharply pointed. Tail filament 89 ± 9 (73–103) long, terminal and directed posteriorly.

Female (based on allotype and 9 paratypes; mean ± SD [range]): Length 3.66 ± 0.53 mm (3.20–4.70 mm), width 198.57 ± 37 (166–278) at level of vulva. Cephalic extremity with 6 prominent triangular lips (Fig. 5 D). Cuticle with annulations, each approximately 11 µm wide. Oesophageal corpus 1133 ± 92.49 (989–1280); isthmus 41 ± 5 (34–48); bulb 120 ± 8 (110–135) long, 146 ± 8 (134–164) wide. Nerve ring, excretory pore and vulva 181 ± 17 (162–220), 1.45 ± 0.21 mm (1.33–1.99 mm) and 3.03 ± 0.45 mm (2.66–4.03 mm), respectively, from anterior end. Reproductive structures confined to body cavity between bulb and anus; vulva posterior, near anus, with prominent prevulvar swelling and small swelling between it and vulva slit (Fig. 7 F). Body with conical termination; anus 162 ± 19 (129–185) from posterior extremity. Eggs oval, 99 ± 6 (90–108) long, 59 ± 4 (54–64) wide, slightly flattened on one side, with terminal operculum.