Thoracostoma trachygaster		Contents		Rev: 03/05/2026
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Thoracostoma Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Leptosomatidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Enoplea

  Enoplia
        Enoplida

            Ironina

                Ironoidea

                     Leptosomatidae

Thoracostomatinae

                  

Thoracostoma trachygaster Hope, 1967

Based on integrative molecular and morphometric analysis, De Oliveira et al (2012) determined that Thoracostoma  trachygaster is actually a species complex containing at least three molecularly and morphologically distinct species.

    Synonyms:

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Morphology and Anatomy:

With general characteristics of the subfamily Thoracostomatinae

• All anterior sensilla papilliform or very short setiform, never long setiform.
• Cephalic capsule well developed with six lobes and without tropis.
• Interlobar grooves divided into furrows and fenestra

Unique to this species:

• Tail and anterior end bluntly rounded
• Males with a scabrous gaster in males; females with cuticular granules surrounding the vulva (Hope, 1967).
• Cephalic capsule well developed, sclerotized
• Amphidial fovea shied shaped
• Two distinct eyespots with pigment cup and refractile body located anteriorly in the neck region.
• Anterior sensilla are arranged in a 6 + 10 pattern and are 2-4 um long.
• Cervical setae in six distinct series between the eyespots and the cephalic suture, in four series (two subdorsal and subventral) after the eyespot, and randomly after the nerve ring.
• Cephalic capsule without distinct anterior lobes, except for the ventral tropis extending to the anterior end of the head, and with six posterior lobes separated by incisions

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Distribution:

Free-living marine nematodes. Often assdociated withy the holdfast of kelp and other algal communities (De Oliveira et al., 2012) .

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Feeding:

Free-living marine nematodes. Epistrate feedrs on surface of kelp and algae.

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Biology and Ecology:

Based on their integrative approach, De Oliveira et al (201) postulate that there are morphological differences amongst genetic lineages within what was previously thought to be one nominal species (T. trachygaster). Consequently, by describing the new species and giving them scientific namesscientific names (T. fatimae and T. igniferum), they ensured that these closely related species are no longer cryptic. They explain that this is important for a wide range of future studies addressing biogeography, biodiversity, phylogeography, and population genetics of nematodes in general, and Thoracostoma in particular.

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Life Cycle:

Ecophysiological Parameters:

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Ecosystem Functions and Services:

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Management:

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References:

De Oliveira, D.A.S., Decraemer, W., Holovachov, O., Burr, J., De Ley, I.T., De Ley, P., Moens, T., Derycke, S. 2012. An integrative approach to characterize cryptic species in the Thoracostoma trachygaster Hope, 1967 complex (Nematoda: Leptosomatidae). Zoological Journal of the Linnean Society 164:18-35.

Hope W.D., 1967. Free-living marine nematodes of the genera Pseudocella Filipjev, 1927, Thoracostoma Marion, 1870, and Deontostoma Filipjev, 1916 (Nematoda: Leptosomatidae) from the West Coast of North America. Transactions of the American Microscopical Society 86: 307-334.

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Copyright 1999 by Howard Ferris.
Revised: March 05, 2026.