Trischistoma gracile Andrássy, 1985

Zhao, Zeng Qi, 2011, A review of the genus Trischistoma Cobb, 1913 (Nematoda: Enoplida), with descriptions of four new species from New Zealand, Zootaxa 3045, pp. 1-25 : 19

Trischistoma gracile Andrássy, 1985

Synonyms

Trischistoma macroseta Vinciguerra & La Fauci, 1978 Trefusia monodelphis Bussau, 1990

Measurements (after Andrássy, 1985)

Females: L = 1000–1200 μm; a = 49–58; b = 4.4–5.3; c = 12–14; c’ = 4.7–5.9; V = 73–78%. Male: L = 800–1100 μm; a = 41–57; b = 3.7–5.2; c = 8–13; c’ = 4–6.

Description (after Andrássy, 1985)

Cuticle very finely annulated, thin. Head rounded, 10–13 μm wide. Six outer labial setae 5–7 μm long (60% of body diameter), four cephalic setae 5–7 μm long, much thinner. Denticles minute. Amphids just behind denticles. Vulva not sclerotized; no postvulval uterine sac. Vulva–anus distance 1.7–2.1 times tail length. Spicules 25–32 μm, gubernaculum 9–12 μm long. No supplements. Tail 82–86 μm long, S-shaped, either strongly bent dorsad, or first dorsad then ventrad.

Diagnosis and Relationships

Trischistoma gracile differs from T. otaika sp. nov., T. monohystera , T. equatoriale in lack of a postvulval uterine sac and shorter body (1000–1200 μm vs 1215–1326 μm, 1500–2100 μm & 1370–1620 μm, respectively).

Females of T. gracile are similar to those of T. triregius sp. nov., T. pellucidum , T. waiotama sp. nov. and T. tukorehe sp. nov. in lacking a postvulval uterine sac. However, T. triregius sp. nov., T. pellucidum , and T. waiotama sp. nov. by have shorter bodies (611–846 μm, 680–850μm & 675–908 μm respectively vs 1000–1200 μm). It differs from T. tukorehe sp. nov. in de Man’s ratios a (49– 58 vs 39–47), b (4.4–5.3 vs 3.8–4.1) and c ’ (4.7–5.9 vs 3.9–4.9).

Trischistoma gracile also can be differentiated from T. tukorehe sp. nov. in having two prominent dorsal teeth not minute denticles.

Habitat and distribution

Aquatic, also in coastal dunes from Europe ( Germany, Hungary, and Italy). Andrássy described this species from an algal mat in a small pool at Fényesfürdő (1985). Etymology

The species epithet gracilis (Latin) means: graceful or charming.