Belongs within: Nematoda.
The Desmodorida are a mostly marine (but sometimes freshwater) group of free-living nematodes. A cephalic capsule is absent in Microlaimoidea but may be present in Desmodoroidea.
Characters (Decraemer & Smol 2006): Body appears yellowish to brownish in glycerin preparations. Body cuticle with transverse striae or annulated, rarely smooth; ornamentation present or absent, mostly without punctation. Anterior sensorial organs arranged in three circlets: the inner labial sensilla papilliform, the six outer labial sensilla and four cephalic sensilla usually setiform, with the four cephalic setae being usually longer than the six outer labial setae. Buccal cavity often with distinct dorsal tooth and smaller ventrosublateral teeth. Pharynx mostly with terminal bulb. Males mostly monorchic, occasionally diorchic. Pre-cloacal papillae or tubules may be present.
<==Desmodorida [Desmodorina]
| i. s.: ProdesmodoraFB90
|--MicrolaimoideaLB02
| |--Ixonema Lorenzen 1971L86 [MicrolaimidaeLB02]
| |--AponchiidaeLB02
| `--Monoposthia [Monoposthiidae]LB02
| `--M. costataL02
`--DesmodoroideaLB02
|--Draconema [Draconematidae]LB02
| |--D. cephalatumL02
| `--D. japonicumTPG10
|--EpsilonematidaeLB02
| |--Perepsilonema Lorenzen 1973L86
| `--MetepsilonemaL86
`--DesmodoridaeHW10
| i. s.: Robbea caelestis Gerlach 1963L86
| Squanema Gerlach 1963L86
|--DesmodorinaeHW10
| |--DesmodoraL02
| | |--D. ovigeraL02
| | `--D. serpentulusL02
| `--Bolbonema Cobb 1920HW10
| |--*B. brevicolle Cobb 1920HW10
| |--B. longisetosum Jensen 1985HW10
| `--B. spiralis Hourston & Warwick 2010HW10
|--SpiriniinaeHW10
| |--Spirina parasitiferaH02
| `--Onyx Cobb 1891HW10
| |--*O. perfectus Cobb 1891HW10
| |--O. cephalispiculus Hourston & Warwick 2010HW10
| |--O. dimorphus Gerlach 1963HW10
| |--O. potteri Hourston & Warwick 2010HW10
| `--O. sagittarius Gerlach 1950HW10
`--StilbonematinaeHW10
|--Stilbonema majumL02
|--Eubostrichus Greef 1869HW10
| |--*E. filiformis Greef 1869HW10
| |--E. africanus Muthumbi et al. 1995HW10
| |--E. dianae Hopper & Cefalu 1973W93
| |--E. longisetosus Berger et al. 1996HW10
| |--E. otti Hourston & Warwick 2010HW10
| |--E. parasitiferus Chitwood 1936W93
| `--E. topiarus Berger et al. 1996HW10
|--Catanema Cobb 1920HW10
| |--*C. exilis Cobb 1920HW10
| `--C. australis Hourston & Warwick 2010HW10
`--Leptonemella Cobb 1920HW10
|--*L. cincta Cobb 1920HW10
|--L. granulosa Boucher 1975HW10
`--L. peronensis Hourston & Warwick 2010HW10
*Type species of generic name indicated
References
Decraemer, W., & N. Smol. 2006. Orders Chromadorida, Desmodorida and Desmoscolecida. In: Eyualem-Abebe, W. Traunspurger & I. Andrássy. Freshwater Nematodes: Ecology and Taxonomy pp. 497–573. CABI Publishing.
[FB90] Freckman, D. W., & J. G. Baldwin. 1990. Nematoda. In: Dindal, D. L. (ed.) Soil Biology Guide pp. 155–200. John Wiley & Sones: New York.
[H02] Hope, I. A. 2002. Embryology, developmental biology and the genome. In: Lee, D. L. (ed.) The Biology of Nematodes pp. 121–145. Taylor & Francis: Florence (Kentucky).
[HW10] Hourston, M., & R. M. Warwick. 2010. New species of free-living aquatic nematodes from south-western Australia (Nematoda: Axonolaimidae and Desmodoridae). Records of the Western Australian Museum 26 (1): 42–69.
[L02] Lee, D. L. 2002. Cuticle, moulting and exsheathment. In: Lee, D. L. (ed.) The Biology of Nematodes pp. 171–209. Taylor & Francis: Florence (Kentucky).
[LB02] Ley, P. de, & M. Blaxter. 2002. Systematic position and phylogeny. In: Lee, D. L. (ed.) The Biology of Nematodes pp. 1–30. Taylor & Francis: Florence (Kentucky).
[L86] Lorenzen, S. 1986. Nematoda: interstitial nematodes from marine brackish and hypersaline environments. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 133–142. E. J. Brill/Dr W. Backhuys: Leiden.
[TPG10] Trebukhova, Y. A., O. N. Pavlyuk & V. V. Galtsova. 2010. Community of free-living marine nematodes on macrophytes (Starka Strait, Peter the Great Bay, Sea of Japan). In: China-Russia Bilateral Symposium: Proceedings of the China-Russia Bilateral Symposium of “Comparison on Marine Biodiversity in the Northwest Pacific Ocean”, 10–11 October 2010, Qingdao (China) pp. 149–153. Institute of Oceanology, Chinese Academy of Sciences; A. V. Zhirmunsky Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences.
[W93] Westphalen, D. 1993. Stromatolitoid microbial nodules from Bermuda—a special micro habitat for meiofauna. Marine Biology 117: 145–157.