Raillietnema		Contents		Rev: 01/10/2026
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Raillietnema Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Cosmocercidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea

Chromadoria

Rhabditida

Spirurina

Cosmocercoidea

                         Cosmocercidae

Cosmocercinae

                          Raillietnema Travassos, 1927

Type species of the genus:  Raillietnema simplex (Travassos, 1925) Travassos, 1927

    Synonyms:
     

Oxysomatium simplex Travassos, 1925

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Morphology and Anatomy:

Although in a different family of the Cosmocercidea (Atractidae), species of Labeonema are considered to be morphologically very similar to Raillietnema of the family Cosmocercidae. One difference is that females of Labonema are monodelpghic prodalphic while those of Raillietnema are didelphic amphidelphic while the postion of the vulva is near mid body in both (Moravec et al., 2025)

From description of Raillietnema kritscheri:

• Small, whitish nematodes.

• Cuticle finely transversely striated; narrow lateral alae present between mid-length of esophagus  to anterior to cloacal opening in males and to level of anus in females.

•  Cephalic end rounded. Oral aperture triangular with 3 small flat lips, each with a broad cuticular membrane (lamella) on inner margin.

•  Four submedian cephalic papillae, 2 on dorsal lip and 1 on each of subventral lip;

• 2 large oval lateral amphids present

• Esophagus with anterior, well-developed and relatively long pharynx; posterior esophageal bulb with sclerotized apparatus.

• Nerve ring at mid-length of esophagus, excretory pore somewhat anterior to level of bulb.

• Tail of both sexes conical and pointed.

Ref: Moravec et al., 2025; Walton, 1949; Anderson et al., 1978

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Distribution:

Species of Raillietnema are mainly considered parasites of amphibians. However, Raillietnema kritscheri reported from freshwater fish in Mexico (Moravec et al., 2025)..

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Feeding:

Food Sources and Feeding strategies for the genus Raillietnema

Intestinal parasites of amphibiaans.

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Biology and Ecology:

Fish in the Lacantun river of southern Mexico reported infected by up to 2000 Raillietnema kritscheri per fish.

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Life Cycle:

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Ecosystem Functions and Services:

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Management:

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References:

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Copyright © 1999 by Howard Ferris.
Revised: January 10, 2026.