Cheironchus		Contents		Rev: 09/07/2024
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Cheironchus Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Selachinematidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea

  Chromadoria

   Chromadorida

    Selachinematidae

Selachonematinae

       Cheironchus Cobb, 1917

Type species of the genus: Cheironchus vorax Cobb, 1917

    Synonyms:
     

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Morphology and Anatomy:

• Body more or less cylindrical, stout.
• Cuticle ornamented with intracuticular dots appearing as ‘asterisks’.
• Amphidial fovea multispiral.
• Short somatic setae or papillae and pores in irregular rows along body.
•  Six inner labial sensilla in form of conical papillae. Outer labial and cephalic sensilla joined in a single crown with cephalic setae much longer than outer labial setae.
• Cheilostom unarmed, narrow and soft-walled.
•  Pharyngostom strongly armed with three mandibles; two large lateroventral mandibles equal in shape and size and shifted laterally; dorsal mandible vestigial.
• Pharynx with anterior and posterior muscular longitudinal  thickenings
• Tail short, ranging from bluntly conical to conical with short cylindrical portion.

	Cheironchus conicaudatus. A: Male; B: Female Scale Bars = 100um       Drawings from Tchesunov and Okhlopkov, 2006   Females:  Didelphic, amphidelphic Ref: Tchesunov and Okhlopkov, 2006
Anterior of male of Cheironchus conicaudatus with extra-pharyngeal muscles relaxed (C) or contracted (D). Drawings from Tchesunov and Okhlopkov, 2006
Males:
Male supplements cup-shaped Body size range for the species of this genus in the database - Click:

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Distribution:

Predatory marine nematodes. Most species described from the Atlantic Coast region of North America.

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Feeding:

Considered voracious predators

For feeding, the mandibles are operated by a powerful complex of pharyngeal muscles. The anterior broadening of the pharynx contains not only normal radial muscular fibres, but also oblique fibres attached to the mandibular arm and apodemes. A muscular envelope surrounds the anterior widening of the pharynx. It consists of longitudinal muscles which originate on the inner side of the somatic cuticle surrounding the mouth and insert on the basal lamina of the pharynx behind its anterior widening.

The longitudinal extra-pharyngeal muscles act to protrude the anterior end of the pharynx and mandibles and to open the mouth and protrude the mandibles in order to capture and then ingest a prey nematode (Tchesunov and Okhlopkov, 2006).

Although not yet studied in the same detail, amd although they lack mandibles, similar muscular origins and insertions probably exist in the generalist predator genus Tripyla and other Tripylidae, to allow expansion of a relatively narrow oral aperture so that prey are exposed to teeth located in the lower part of the buccal cavity.

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Biology and Ecology:

Free-living predator nematdes feeding on nematode prey

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Life Cycle:

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Ecosystem Functions and Services:

Predator.

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Management:

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References:

Tchesunov, A.V. and Okhlopkov, J.R. 2006. On some selachinematid nematodes (Chromadorida: Selachinematidae) deposited in the collection of the Smithsonian National Museum of Natural History. Nematology 8:21-24.

Copyright 1999 by Howard Ferris.
Revised: September 07, 2024.