Rev: 04/03/2023
Trischistoma Cobb, 1913
Synonyms:
Tripylina Brzeski, 1963 is considered an invalid synonym
In Trischistoma, the females are monovarial, prodelphic and the whorls of six outer labial and four cephalic setae are well separated (Andrassy, 2007; Cid del Prado et al., 2010; and Cid del Prado et al., 2016).
In the genus Tripylina Brzeski, 1963 (family Trischostomatidae), the outer labial and cephalic whorls of six and four setae are close together, almost in a single whorl (Tsalolikhin 1983; Zullini 2006; Cid del Prado-Vera et al. 2010; 2012).
Cuticle smooth, sometimes with setae.
Three conical lips, each with 2 papillae, not set off from body contour.
Outer labial and cephalic setae in two whorls, separated from each other, 6 in the first and four in the second.
Stoma narrow with dorsal tooth and small stomal denticles; can open wide to ingest prey.
Trischistoma has a single gonad, a smooth cuticle, small stomal denticles and the whorls of setae separated; and DEGO at tip of buccal tooth.
Esophagus cylindrical with three glands overlapping intestine.
Monovarial, prodelphic, with or without post-uterine sac.
Caudal glands open through spinneret at tail tip.
Rare. Supplements anterior to cloaca.
Occur in some species.
Key to Trischistoma species (from Cid del Prado et al., 2016)
1. Body a tight spiral shape after death.T. helicoformis n. sp.
Body not spiral-shaped after death..2
2. Post-uterine sac present......................3
Post-uterine sac absent....................7
3. Body length > 2.0 mm......4
Body length < 2.0 mm....5
4. Body length 2.9-3.2 mm; tail length 220-242 µm.T. subtillissimum Andrassy, 2011
Body length 4.0-4.1 mm; tail length 250-260 µm...T. tenuissimum Andrassy, 2011
5. Male absent; V = 75%; tail length 81-98 µm.. T. otaika Zhao, 2011
Male present; body length 1.0-1.9 mm.�6
6. Body length 1.4-1.9 mm; a = 45-77; female tail length 115-150 µm, spicules 25-35 µm long; male tail with one supplement. T. monohystera (de Man, 1880) Schuurmans-Stekhoven, 1951
Body length 1.4-1.6 mm; a = 38-44; V = 81-83%; female tail length 80-96 µm; spicules 40-44 µm long; male tail with 2-3 supplementsT. equatoriale Andrassy, 2006
Body length 1.0-1.3 mm; a = 41-54; female tail length 63-104 long; spicules 29-34 µm long� T. veracruzense Cid del Prado-Vera, Ferris & Nadler, 2010
Body length 1.0-1.1 mm; a = 49-53; c = 12-13, female tail length 82-86 µm; spicules 25-32 µm long� T. gracile Andrassy, 1985
7. Body length < 1.0 mm.....8
Body length > 1.0 mm..10
8. Body length 0.4-0.6 mm; female tail length 40-50 µm�T. minor Tahseen & Nusrat, 2010
Body length 0.6 -0.9 mm; V = 73-80%......9
9. Cervical setae absent; pharynx length 155 µm; tail length 50-60 µm; b = 4.4-4.8�T. pellucidum Cobb, 1913
Single latero-ventral cervical setapresent; pharynx length 171-198 µm; tail length 50-64 µm �T. waiotama Zhao, 2011
Paired lateral cervical setae present; pharynx length 137-219 µm; tail length 44-72 µm. T. triregius Zhao, 2011
10. Body length 0.80-1.2 mm; a = 34-45; V = 67-73%; female tail length 51-84 µm..... . T. corticulensis n. sp.
Body length 1.0-1.1 mm; a = 39-59; female tail length 34-92 µm...11
11. a = 45-59; c = 17-29; b = 4.1-4.8; V = 67-73%; female tail length 34-57 µm� T. ripariana n. sp.
a = 39-47; c = 11-15; b = 3.8-4.1; V = 72-76%; female tail length 75-92 µm � T. tukorehe Zhao, 2011
Moist soils with organic material and on tree and rock surfaces associated with mosses and lichens..
Predators of small organisms, including nematodes (Yeates et al., 1993; Cid et al., 2010).
Predation and population regulation of prey species.
Brzeski, M.W. (1965): On the identity of Trischistoma Cobb and Tripylina Brzeski. Nematologica 11:449.
Cid del Prado, I., H. Ferris and S.A. Nadler. 2010. Soil inhabiting nematodes of the genera Trischistoma, Tripylina and Tripyla from M�xico and the USA with descriptions of new species. Journal of Nematode Morphology and Systematics 13-28-49.
Cid del Prado-Vera, I., Ferris, H., Nadler, S.A. 2016. Five new species of the family Trischistomatidae (Nematoda: Enoplida) from North and Central America, with keys to the species of Trischistoma and Tripylina. Zootaxa 4109(2):173-197.
Tsalolikhin, S.Y. (1983). Nematodes of the Families Tobrilidae and Tripylidae of the World Fauna. Nauka, Leningrad, Russia, No.138. 232p.
Yeates, G.W., T. Bongers, R. G. M. De Goede, D. W. Freckman, and S. S. Georgieva. 1993. Feeding habits in soil nematode families and genera—An outline for soil ecologists. Journal of Nematology 25:315-331.
Zullini, A. (2006) Order Triplonchida. In: Abebe, E., Andrassy, I. & Traunspurger, W. (Eds), Freshwater Nematodes, Ecology and Taxonomy. CABI Publishing, Wallingford, UK , pp 293-323.