Belongs within: Cycloneuralia.
The Desmoscolecida are a group of mostly marine nematodes with a heavily ornamented cuticle and sclerotised head cap.
Characters (from Carlton 2007): Cuticle usually striated, with or without prominent setae on peduncles, spines, scales, wart-like protrusions or desmens; inner and outer labial cephalic sensilla obscure, paralabials setiform, or if outer labials apparent, then often situated on peduncles; amphids vesiculate or circular; stoma very small, unarmed; rugae absent; caudal glands not projected anterior to rectum; female reproductive system didelphic, amphidelphic, gonoducts outstretched or reflexed; male reproductive system monorchic or diorchic.
<==Desmoscolecida [Desmoscolecina, Desmoscolecoidea] |--CyartonematidaeLB02 |--DesmoscolecidaeLB02 | |--Greeffiella dasyura Cobb 1922L86 | `--Desmoscolex Claparède 1863 [Desmoscolecinae]E86 | `--D. aquaedulcis Stammer 1935E86 `--MeyliidaeLB02 |--Haptotricoma Lorenzen 1977L86 | `--H. arenariaL86 `--Desmotimmia Freudenhammer 1975L86 `--D. mirabilisL86
*Type species of generic name indicated
References
Carlton, J. T. 2007. The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon 4th ed. University of California Press.
[E86] Eder, R. 1986. Nematoda from continental subterranean aquatic habitats. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 125–132. E. J. Brill/Dr W. Backhuys: Leiden.
[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.