Croconema cinctum Cobb, 1920

Armenteros, Maickel, Ruiz-Abierno, Alexei & Decraemer, Wilfrida, 2014, Revision of Desmodorinae and Spiriniinae (Nematoda: Desmodoridae) with redescription of eight known species, European Journal of Taxonomy 96, pp. 1-32 : 10-13

Croconema cinctum Cobb, 1920 Figs 4 , 5 , Table 1

Croconema cinctum Cobb, 1920: 332 .

Desmodora (Croconema) cincta – Gerlach, 1963: 87.

Material examined

10 ♂♂, 9 ♀♀ and 10 juveniles, deposited in the nematode collection at Centro de Investigaciones Marinas, Universidad de La Habana, CUBA.

Description

Cuticle coarsely striated (annuli ~ 2 μm width). Head capsule well-developed and relatively extended longitudinally.Inner labial sensilla papilliform. Outer labial sensilla setiform papillae and minute (1–2 μm long). Four cephalic setiform sensilla (5–10 μm long); three circlets of eight subcephalic setae (5–10 μm long) on the head capsule: the first circle very close to cephalic sensilla, the second circle posterior to the amphidial fovea and the third circle close to the posterior border of the capsule. Amphidial fovea cryptospiral, relatively small and located ahead in the capsule. Eight longitudinal rows of short somatic setae (4–5 μm long) running along body length, at the posterior region continuing as six rows. Buccal cavity narrow, elongate, with one dorsal tooth and two minute ventrosublateral teeth. Pharynx muscular with posterior bulb. Cardia extended. Secretory-excretory system not observable. Tail non-striated in the last third, conspicuously punctuated and with few scattered subterminal setae (2–3 µm long).

Male monorchic, anterior testis to the right of the intestine. Spicule curved, slightly cephalated, gubernaculum a narrow cuticularized rod. Two ventromedian precloacal supplements formed by the

enlargement/protrusion of three consecutive annuli (mid one larger than others) (only one supplement is depicted in Fig. 4E ).

Female didelphic, ovaries antidromously reflexed, anterior genital branch to the left, posterior to the right, vulva a transversal slit.

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

Remarks

Verschelde et al. (2006) proposed a dichotomous key and a table with diagnostic features for the genus Croconema . Cuban specimens are quite similar to the holotype described by Cobb (1920) and to those described from the Maldives ( Gerlach 1963) and the Red Sea ( Gerlach 1964). We noted in some specimens the presence of additional smaller setae at the base of the subcephalic setae ( Fig. 4 B–C), but we could not reveal more evidence to allow identification with another Croconema species.

Figures

Fig. 4. Croconema cinctum Cobb, 1920, ♂ specimen 1 (A, B & D) and specimen 2 (C & E). A. Habitus. B. Neck region. C. Head. D. Tail region. E. Copulatory apparatus.

Fig. 5. Croconema cinctum Cobb, 1920, SEM microphotographs of ♂ specimen 1 (A, B & D) and specimen 2 (C). A. Labial region, en face view. B. Head capsule, lateral view. C. Cuticle striation at mid-body region. D. Part of tail tip.