Trichocephalida

Trichocephalida
	Trichosomoides crassicauda, young female with male in vagina, drawing in Hall, 1916
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Nematoda
Class:	Enoplea
Subclass:	Dorylaimia
Order:	Trichocephalida
Families
	Anatrichosomatidae Yamaguti, 1961; Capillariidae Railliet, 1915; Cystoopsidae Skrjabin, 1923; Trichinellidae Ward, 1907; Trichosomoididae Hall, 1916; Trichuridae Ransom, 1911
Synonyms
	Trichinellida; Trichiurida

The Trichocephalida (Trichinellida or Trichurida in other classifications) is an order of parasitic nematodes.

Taxonomy

The order Trichocephalida includes, according to modern classifications,^[2] the single suborder Trichinellina Hodda, 2007, which itself includes the single superfamily Trichinelloidea Ward, 1907, which itself includes 6 families:

Family Anatrichosomatidae Yamaguti, 1961 (1 genus, 5 species) including the single genus Anatrichosoma
Family Capillariidae Railliet, 1915^[3] (1 subfamily, 18-22 genera according to classifications,^[4] 390 species) including Capillaria
Family Cystoopsidae Skrjabin, 1923 (2 subfamilies, 2 genera, 7 species)
Family Trichinellidae Ward, 1907 (4 genera, 16 species) including Trichinella
Family Trichosomoididae Hall, 1916^[1] (2 subfamilies, 5 genera, 25 species) including Huffmanela
Family Trichuridae Ransom, 1911 (1 subfamily, 6 genera, 107 species) including Trichuris

Note that another slightly different arrangement of families exists,^[4] with the Family Trichosomoididae including Anatrichosoma in a subfamily Anatrichosomatinae.

Biology

Male caudal extremity of *Eucoleus aerophilus*, the nematode causing pulmonary capillariasis in foxes. Bar = 50 μm

All members of this order are histiotrophic, meaning that in at least one stage of their life cycle, they develop in cells or tissues. They are all parasites in vertebrates in their adult stage. The anterior end is narrower than the posterior end in most of these worms, and the esophagus is slender and embedded in cells called stichocytes which form a stichosome. Eggs of members of this order have bipolar or biopercular plugs (except in a few species).

References

^ ^a ^b Hall, M.C. 1916: Nematode parasites of mammals of the orders Rodentia, Lagomorpha and Hyracoidea. Proceedings of the U.S. National Museum, 50, 1–247 Free PDF.
^ Hodda, M. 2011: Phylum Nematoda Cobb 1932. In: Zhang, Z.-Q. (ed.) 2011: Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa, 3148: 63–95. ISBN 978-1-86977-849-1 (paperback) ISBN 978-1-86977-850-7 (online edition) Free PDF
^ Railliet, A. 1915: L'emploi des médicaments dans le traitement des maladies causées par des Nématodes. Recueil de Médecine Vétérinaire, Paris, 91, 490–513. [not seen]
^ ^a ^b Moravec, F. 2001: Trichinelloid Nematodes parasitic in cold-blooded vertebrates. Academia, Praha, 432 pp. (list of genera of Capillariidae in pages 30-32) (ISBN 8020008055)

[Hall1916-1] Hall, M.C. 1916: Nematode parasites of mammals of the orders Rodentia, Lagomorpha and Hyracoidea. Proceedings of the U.S. National Museum, 50, 1–247 Free PDF.

[2] Hodda, M. 2011: Phylum Nematoda Cobb 1932. In: Zhang, Z.-Q. (ed.) 2011: Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa, 3148: 63–95. ISBN 978-1-86977-849-1 (paperback) ISBN 978-1-86977-850-7 (online edition) Free PDF

[3] Railliet, A. 1915: L'emploi des médicaments dans le traitement des maladies causées par des Nématodes. Recueil de Médecine Vétérinaire, Paris, 91, 490–513. [not seen]

[Moravec2001-4] Moravec, F. 2001: Trichinelloid Nematodes parasitic in cold-blooded vertebrates. Academia, Praha, 432 pp. (list of genera of Capillariidae in pages 30-32) (ISBN 8020008055)

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