Trissonchulus latus ( Wieser, 1953 ) Inglis 1961

Abolafia, Joaquín, Ruiz-Cuenca, Alba N., Fernandes, Berenice M. M., Cohen, Simone C. & Cárdenas, Melissa Q., 2015, Description of free-living marine nematodes found in the intestine of fishes from the Brazilian coast, Zootaxa 3948 (3), pp. 549-572 : 557-561

Trissonchulus latus ( Wieser, 1953) Inglis 1961

( Figs 5–7 )

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

Measurements. See Table 2 .

Description. Adults: Body 2.10–3.04 mm long. Cuticle smooth, lacking striations and ornamentations. Lip region with labial papillae and short cephalic setae, the labial and lateral cephalic ones single, the subdorsal and subventral ones double. Amphids well developed, pocket shaped with oval aperture occupying one third of lip region diameter. Stoma long and narrow, comprising two regions; anterior as long as wide with three refringent claw-like teeth, and posterior tubular, length five times lip region diameter. Pharynx more or less cylindrical, slightly expanded at its base. Nerve ring surrounding pharynx in its anterior part. Excretory pore not observed. Cardia poorly developed, conoid. Intestine not differentiated, generally in bad condition.

Female: Body with sigmoid or C-shaped habitus. Reproductive system didelphic-amphidelphic; ovaries straight with one or two rows of oocytes; oviducts narrow, separated from uterus by a sphincter; uteri slightly swollen, length about 2–3 times corresponding body diameter, bearing well developed eggs, 177–192 x 69 –91 Μm. Rectum short, less than one anal body diameter. Tail conoid with rounded terminus. Spinneret aperture at tail tip.

Male: General morphology similar to female, also with sigmoid habitus. Spicules short and broad, about 3 times longer than wide and slightly ventrad curved. Gubernaculum short, slightly less than the spicule length, distally more developed. Tail conoid, ventrally straight and dorsally convex, with rounded terminus. Precloacal papillae disposed in two pairs subventral rows. Adcloacal papilla at anterior cloacal lip. Postcloacal papillae disposed in two ventroanterior pairs, one subventral pair, three ventroposterior pairs, and one dorsal terminal pair. Spinneret aperture at tail tip.

Distribution. T. latus was reported from Chile by Wieser (1953) in sublittoral soft sediment. This is its first report from Brazil (see Venekey et al. 2010).

Remarks. The material examined is similar to the type material examined by Wieser (1953), but differs in the smaller size of males (2.09–2.83 mm vs 4.92 mm), smaller spicule (62–86 µm vs 137 µm) and tail slightly shorter (62–76 µm vs 90 µm). This could be intraspecific variability because only one male was previously described.

Figures

FIGURE 5. Trissonchulus latus (Wieser, 1953) Inglis 1961. A: Entire male. B: Entire female. C: Stoma. D: Amphid. E: Neck. F, G: Male posterior end (lateral and ventral views, respectively). H: Female posterior end.

FIGURE 6. Trissonchulus latus (Wieser, 1953) Inglis 1961 (LM). A, B: Stoma. C: Neck. D: Vagina (arrow). E, F: Egg. G, H: Female posterior end. I, J: Male posterior end (lateral and ventral views, respectively).

FIGURE 7. Trissonchulus latus (Wieser, 1953) Inglis 1961 (SEM, male). A – D: Anterior end (lateral, dorsal, ventral sublaterofrontal views, respectively. E: Cuticle. F, G: Lip region in frontal view. H: Male posterior end. I, J: Male tail (lateral and subventral views, respectively). K, L: Male tail terminus (ventral and dorsal views, respectively).