Family Desmoscolecidae

                                 Revised 01/12/26

Classification:

Phylum Nematoda

  Class Chromadorea

    Subclass Chromadoria

     Order Desmoscolecida

        Superfamily Desmoscolecoidea

Desmoscolecidae Shipley, 1896

• mainly marine nematodes

• have somatic setae

• heavily ornamented and annulated cuticle, sometimes with scales, warts or spines and particle incustations (desmen).

• Head offset, cephalic helmet or head cap; four cephalic setate.

• Amphid apertures rounded or elongate.

• Pigment spots (ocelli) may be present near junction of espohagus and intestine.

• Stoma very small, cavity almost absent.

• Esophagus tubular and short.

• Tail with caudal glands and terminal spinneret

• Females amphidelphic, didelphic, ovaries outstretched

• Males without supplements; monorchic or diorchic.

• Typically marine, some freshwater and soil, e.g. Desmoscolex vinealis from a vineyard soil in Germany and from rhixosphere of hedges in Austria and Belgium.(Decraener and Rho, 2013)

A unique group of nematodes characterized by desmens, thick transverse rings consisting of sedimentary particles and cementing material.. Cephalic tubercles (setae) are a useful diagnostic feature in taxonomy (Shirayama and Hope, 1992). Some genera spines (Grefiellla), scales (Paratricoma) or warts (Pareudesmoscolex) on the cuticle (Decraemer, 1978).

Two subfamilies are recognized:

• Subfamilu Desmoscolecinae

  • Desmen separated by a zone of 2 to 5 annules which may be ornamented with pores and spines

  • Esophagus short

  • Males monorchic

  • Subfamily separated into two tribes:

    • Tribe Desmoscolecini

      • Body ornamented with a band of desmens or with concretion scales of secretions and fine particles, with pores or hairy spnes

      • Somatic setae glandular, subdorsal and subventral

      • Caudal glands often reduced

      • Type genus of the tribe: Desmoscolex

    • Tribe Greeffiellini

      • Adult cuticle with shallow annulation, lacking desmen but covered with spines or scales

      • Four cephalic setae, jointed or not, inserted in head

      • Somatic setae reduced in number, subventral setae usually absent in female

      • Type genus of the tribe: Greeffiella

• Subfamily Tricominae

  • Desmen separated by a narrow, smooth zone of a single annule.

  • Esophagus longer

  • Males diorchic

  • Body cuticle with shallow annules ornamented with desmen, hairy spines or scales

  • Somatic setae with tricomoid pattern

  • Type genus of the subfamily: Tricoma

	Anterior view of head
Desmoscolex sp. from depths of Western Pacific Ocean
Photomicrographs by Shirayama and Hope, 1992
Tricoma sp.: Somatic setae (from Cesaroni et al., 2017)

    Go To Dictionary of Terminology 

References

Cesaroni, L. Guidi, L., Balsamo, M., Semprucci, F. 2017. Scanning electron microscopy in the taxonomical study of free-living marine nematodes. Microscopie 28:6970

Decraemer, W. 1978. Morphological and taxonomic study of the genus Tricoma Cobb (Nematoda : Desmoscolecida), with the description of new species from the Great Barrier Reef of Australia. Australian Journal of Zoology Supplementary Series 26(55) 1-121.

Decraemer, W. 1985. Revision and phylogenetic systematics of the Desmoscolecida (Nematoda). Hydrobiologia 120:259-283.

Decraemer, W. and Rho, H.S. 2013. 7.11 Order Desmoscolecida. In Schmidt-Rheas and de Gruyter, W. Handbook of Zoology.Gastrocticha, Cycloneuralia, Gnatifera. Volume 2: Nematoda

Decraemer, W. and Tchesunov, A.V. 1996. Some desmoscolids from the  White Sea (Nematoda: Desmoscolecida). Russian J. Nematology 4:115-130.

Shirayama, Y. and Hope. W.D. 1992. Cephalic tubercles: a new character useful for the taxonomy of Desmoscolecida (Nematoda). Trans. Am. Microscop. Assoc: 111:211-222..

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