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Secernentea

{{short description|Class of roundworms}}

{{Automatic taxobox

| image = Celegans wt nhr80rnai.png

| taxon = Secernentea

| authority =

| subdivision_ranks = Subclasses

| subdivision =

Diplogasteria (disputed)

Rhabditia (paraphyletic?)

Spiruria

Tylenchia (disputed)

and see text

}}

Secernentea was a class of nematodes in the Classical Phylogeny System (Chitwood, 1958) and is no longer in use.{{cite web|title=WoRMS - World Register of Marine Species - Secernentea|access-date=May 24, 2018|url=http://www.marinespecies.org/aphia.php?p=taxdetails&id=2133}}{{cite journal |author=Olsen, Oliver Wilford |date=Dec 1975 |title=Animal Parasites: Their Life Cycles and Ecology |journal=The Quarterly Review of Biology |publisher=Courier Corporation |volume=50 |issue=4 |doi=10.1086/408868}} This morphological-based classification system has been replaced by the Modern Phylogeny system, where taxonomy assignment is based on small subunit ribosomal DNA (SSU rDNA).De Ley, P., and M. Blaxter. 2004. "A New System for Nematoda: Combining Morphological Characters with Molecular Trees, and Translating Clades into Ranks and Taxa." Nematology Monographs and Perspectives 2. Brill, Netherlands: 633–53.De Ley, P., Wilfrida Decraemer, and A. Eyualem. 2006 "Introduction: Summary of Present Knowledge and Research Addressing the Ecology and Taxonomy of Freshwater Nematodes." CABI.

Description

Amphid apertures of Secernenteas are pore or slit-like.

Some Secernenteas have deirids which are located near nerve ring.

Secernenteas have posterior phasmids.

The excretory system of a Secernentea is tubular.

Cuticles of Secernenteas are striated in two to four layers. Lateral field is present.

Secernenteas have three esophageal glands. Their esophageal structure varies.

Male Secernenteas generally have one testis.

Caudal alae are common in Secernenteas.

Sensory papillae of Secernenteas are cephalic only. It might be caudal papillae in male Secernenteas.

Secernenteas are mostly found in land but they are rarely found in marine water or freshwater.

Taxonomy

{{see also|List of nematode families}}

Subclasses and orders of Secernentea are:Tree of Life Web Project (ToL) (2002): [http://tolweb.org/Nematoda/2472/2002.01.01 Nematoda] {{Webarchive|url=https://web.archive.org/web/20130508231436/http://tolweb.org/Nematoda/2472/2002.01.01 |date=2013-05-08 }}. Version of January 1, 2002. Retrieved November 2, 2008.

Some families traditionally considered to be Rhabditida seem to be closer to the Tylenchida. If the Tylenchia are to be maintained as separate, they probably will be included therein.

See also

References

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{{Helminthiases}}

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Category:Ecdysozoa classes

Category:Obsolete animal taxa

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