Desmodora pontica Filipjev 1922

Desmodora pontica Filipjev, 1922

Figs 6A–B, 7, Table 1

Desmodora pontica Filipjev, 1922: 119.

Desmodora (Pseudochromadora) pontica – Gerlach 1963: 84.

Material examined

10 ♂♂, 10 ♀♀ and 11 juveniles, deposited in the nematode collection at Centro de Investigaciones Marinas, Universidad de La Habana, CUBA.

Description

Cuticle coarsely striated (annuli ~ 2 μm width) in the anterior region but finer at mid-body region (annuli ~ 1 µm width). Strong head capsule with labial region clearly marked by a suture. Inner labial setae papilliform. Outer labial sensilla relatively long (2–3 µm long). Four cephalic setae (4–8 μm long); one circle of four subcephalic setae (4–8 μm long) posterior to the amphidial fovea. Amphidial fovea cryptospiral. Eight longitudinal rows of short somatic setae (2–4 μm long) running along the entire body length, continuing as four rows on the tail region. Buccal cavity narrow, elongate, with one dorsal tooth and two minute ventrosublateral teeth at the same level. Pharynx muscular with posterior bulb and plasmatic interruptions, internal lining well sclerotized. Cardia extended. Secretory-excretory system not observable. Posterior half of tail conspicuously punctuated and without striation.

Male monorchic, anterior testis to the left of the intestine. Spicule strongly curved and cephalated. Gubernaculum a narrow rod. No supplements.

Female didelphic, ovaries antidromously reflexed, both genital branches to the right of the intestine. Vulva a transversal slit.

Juveniles are similar to adults, except for the development of the reproductive system.

Remarks

Suctorians (Ciliophora) are common commensals on D. pontica. The genus Desmodora de Man, 1889 is speciose, with a complicated taxonomy. It has included several subgenera later raised to genus level by Verschelde et al. (1998) (e.g., Croconema, Pseudochromadora and Zalonema) and a plethora of bad descriptions and doubtful species. The most comprehensive study about Desmodora has been made by Verschelde et al. (1998) and an outdated dichotomous key was provided by Wieser (1954). Our specimens resemble the descriptions of D. pontica by Schuurmans Stekhoven (1950) and Gerlach (1952). The female specimen depicted and described by Boucher (1975) as D. pontica differs in two important features: outer labial sensilla are considerable longer (i.e., as long as the cephalic setae) and the posterior border of the head capsule reaches the first cuticle annuli. Based on our material, males seem to have amphidial fovea well in the central part of the head capsule (i.e., no contact with the striation) and juveniles and females tend to have amphidial fovea posterior on the capsule (i.e., touching the first annuli).