Key for identification of species of Trischistoma

1. Body length> 1.2 mm; postvulval uterine sac present......................................................... 2

– Body length <1.2 mm; postvulval uterine sac absent.......................................................... 4

2. Tail length 5–7 anal body diameters; postvulval sac <50% vulva-anus distance.......................... T. monohystera

– Tail length 3–4.5 anal body diameters; postvulval sac>50% vulva-anus distance................................... 3

3. a = 38–44; b = 4.9–5.8; c = 15.2–20.6; c’ = 3.2–3.8; V = 81–83%...................................... T. equatoriale

– a = 44–49; b = 4.7–4.8; c = 12.3–14.9; c’ = 4.2–4.6; V = 73–76%................................... T. otaika sp. nov.

4. Body length>1.0 mm.................................................................................. 5

– Body length <1.0 mm.................................................................................. 6

5. Minute denticles in mouth cavity; a = 49– 58, b = 4.4–5.3; c = 4.7–5.9.................................... T. gracile

– Prominent denticles in mouth cavity; a = 39–47; b = 3.8–4.1; c = 3.9–4.9.......................... T. tukorehe sp. nov.

6. Cervical setae absent......................................................................... T. pellucidum

– Cervical setae present.................................................................................. 7

7. Cervical setae paired, lateral.............................................................. T. triregius sp. nov.

– Cervical seta single, ventral............................................................. T. waiotama sp. nov.