Croconema torquens (Gerlach, 1963) Verschelde, Gourbault & Vincx 2006

Croconema torquens (Gerlach, 1963) Verschelde, Gourbault & Vincx, 2006

(Figs 8–10)

Material examined. Ten females and ten males were examined from Diapterus rhombeus.

Measurements. See Table 2.

Description. Adults: Body 1.22–1.84 mm long. Cuticle with transverse striations forming well developed annuli, having two morphologies: with the anterior margin dentate in the anterior half of body and with the posterior margin dentate in the posterior half; somatic setae present over whole body. Lateral field only seen with SEM, occupying one third body diameter. Anterior end swollen, forming a cephalic capsule lacking transversal striations and bearing short setae. Lip region with six fused lips carrying short setiform papillae. Amphids with sexual dimorphism, smaller in females and larger in males (see description below). Stoma differentiated into two parts, anterior short and wide bearing small teeth, and posterior longer with reduced lumen and very muscular. Pharynx short, scarcely more than twice body diameter at its base, expanded posteriorly in a bulb slightly longer than wide. Nerve ring not observed clearly. Excretory pore not observed. Cardia poorly developed. Intestine in bad condition.

Female: Body with helical habitus. Amphids reduced, spiral, a quarter of lip region daimeter, located at base of lateral lips. Reproductive system didelphic-amphidelphic; ovaries short and not reflexed; oviducts thin; a small sphincter separates each oviduct and uterus; uteri short and swollen with spermatozoa inside; vagina very reduced. Rectum short, less than one anal body diameter. Tail conoid, slightly ventrad curved and ending in a conoid spinneret.

Male: General morphology similar to female, also with helical habitus. Amphids well developed, elliptical, about half lip region width and occupying more than half of the cephalic capsule length. Spicules sickle-shaped, with rounded manubrium, short calamus and ventrad curved lamina with acute tip. Gubernaculum short, less than half of spicule length. Copulatory and precloacal thorns present. Tail conoid, slightly ventrad curved and ending in a conoid spinneret.

T. latus C. torquens D. pellucida P. breviamphida Diapterus rhombeus Diapterus rhombeus Diapterus Eucinostomus Diapterus rhombeus argenteus rhombeus Distribution. Croconema torquens was previously reported by Gerlach (1963, 1964) from the Maldives and the Red Sea. This is its first report from Brazil (see Venekey et al. 2010).

Remarks. This material is similar to that described by Gerlach (1963, 1964) although differing in: anterior vulva position (V= 54–66 vs 86), with longer (72–83 vs 55 µm) and more ventrad curved spicules.