Gyrinicola tba ( Dinnik 1930 )

Brigitte, Planade, Odile, Bain, Jean-Paul, Lena & Pierre, Joly, 2008, Gyrinicola chabadamsoni n. sp. and G. t b a (Dinnik 1933) (Nematoda, Oxyuroidea) from tadpoles of the hybridogenetic complex Rana lessonae-esculenta (Amphibia, Ranoidea), Zootaxa 1764, pp. 25-39 : 27

Gyrinicola tba ( Dinnik 1930) , Oxyurida, Oxyuroidea , Pharyngodonidae .

Synonym Thelandros tba Dinnik 1930 .

Description. Female ( Fig. 1 , Table 2 ). Head: Four large submedian papillae; cylindrical salient and soft amphids. Mouth: triangular to pentagonal; very thin cuticular buccal membrane composed of one dorsal and two latero-ventral lips with conspicuous deeper folds in the 3 angles determined by the dorsal and the two sublateral sides of mouth; each cuticular lip constricted centrally or interrupted and forming two parts; below the median divisions, anterior apex of buccal wall with single or double furrows. Transverse section of buccal cavity triangular. Very long tail abruptly attenuated posterior to anus. Female reproductive system: muscular short vagina, ovijector 450 µm long; two unequal uteri ending in a chamber lined with large epithelial cells. Large genital tract: thick ovary with apex at level of rectum, directed anteriorly, then bent; oviduct at level of excretory cell, with a particular enlarged section at midlength with pseudocoelomocytes nearby; uterus coiled at level of anterior part of intestine, then directed backwards; in larger females, posterior coils of uteri are also found. Slender genital tract folded in the region of the vagina, thus only parts of the thin ovary or oviduct can be identified in intact specimens; after dissection, the complete tract can be identified: thin ovary with a distal file of few ovulae, thin oviduct with a distinct enlarged section and pseudo-coelomocytes, thin uterus containing a few divided eggs inside a thin shell and embryos, some of them aborted; no larvae identified.

Male ( Fig. 3 , Table 3 b). Testis directed forwards then flexed; wide ejaculatory duct, with conspicuous vacuolated walls. No spermatozoa identified in the ejaculatory duct nor in the seminal vesicle. Genital cone: distal extremity of postcloacal lip pointed and flexed backward; two pairs of papillae, one precloacal, one postcloacal. Shape of the cone-tail junction and position of caudal papillae: the posterior lip, posterior aspect of the cone and tail delineate a rectangle; one pair of papillae joined on a single salient nipple located near the right angle formed by the cone-tail. Spicule thick, regularly attenuated with round distal extremity.

Eggs ( Fig. 1 ). Thick-shelled eggs wide, almost spherical; dotted surface; transverse section triangular due to 3 thick lateral shell crests; operculum near apex, sligtly elliptical; one cell in uteri, two to four cells near vagina.

Taxonomic discussion. The body measurements of both sexes are given in Table 2 and 3 b. In the female, the tail is abruptly constricted behind the anus. The long thin caudal filament and the male caudal morphology both correspond to the descriptions of G. t b a by Dinnik (1930) and Volgar (1959).

Female didelphy is confirmed; the two genital tracts are unequal; the thin ventrally folded uterus is tubular and elongated. In our specimens, collected in June and August, the slender uterus did not contain larvae or adults.

Figures

FIGURE 1. Mature females. A – I, Gyrinicola chabadamsoni n. sp. A. Habitus left lateral view (anatomical genital parts shown: beginning of the thick ovary, thick-shelled eggs, embryos and males, V 10 FIII). B. C. D. Head in lateral, median and apical view, respectively (V 10 FII). E. Mouth surrounded with flaps showing the internal crests (V 10 FII). F. Base of the buccal cavity (V 10 FII). G. Tail ventral view (V 10 FIII). H. Thick-shelled egg two cells stage (V 10 FII). I. Detail of operculum in lateral view (V 10 FII). J – Q, G. t b a. J. Habitus left lateral view (anatomical genital parts shown: beginning of the thick ovary, thick-shelled eggs, V 60 FI). K. Head apical view (V 402). L. Mouth and cuticular lips of another specimen (E 6 FII). M. Base of buccal cavity (V 402). N. Head in lateral view (V 402). P. Thick-shelled egg four cells stage (V 16 FII). Q. Detail of operculum in sub-median view (V 16 FII). Scales in Μm A, J, 200, B – F, K – N, I, Q, 20, G, O, 150, H, P, 50.

FIGURE 3. Free males. A – E, Gyrinicola chabadamsoni n. sp. A. Habitus left lateral view. B. Cephalic region. C. Tail ventral view. D. Posterior region right lateral view. A to D male V 10 MI. E. Posterior region of holotype, left lateral view (V 17 MIII). F – I, G. t b a male E 12 MI. F. Habitus right lateral view. G. Cephalic region. H. Genital cone's region right lateral view. I. Idem semi-ventral view. Scales in Μm A, F, 150, B, C, D, G, H, I, 20, E, 50.