The Chromadorea are a class of the roundworm phylum,
Nematoda. They contain a single
subclass (Chromadoria) and several orders. With such a redundant arrangement, the Chromadoria are liable to be divided if the orders are found to form several
clades, or abandoned if they are found to constitute a single radiation.
Formerly, they were treated as a subclass in the
paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
"
Adenophorea" assemblage, which has been mostly abandoned by modern authors. It is also suspected that the Chromadorea may not be
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...
as delimited here; at least the
Monhysterida
The Monhysterida are an order in the phylum Nematoda. Usually the stoma
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stem ...
seem to be a distinct and far more ancient lineage than the rest.
Members of this class' bodies usually have annules, their
amphids elaborate and spiral, and they all have three
esophageal glands. They usually live in marine sediments, although they can live elsewhere. They have a more sophisticated
pharynx
The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its ...
than most roundworms.
Members of this class can be identified by the presence of eight
conserved signature indels (CSIs) exclusively shared by the class.
These molecular markers are found in essential proteins such as
tRNA (guanine-N(1))-methyltransferase and can serve as a reliable molecular method of distinguishing the Chromadorea from other classes within the phylum Nematoda.
Orders
Provisionally, the following orders are placed here:
*
Araeolaimida
Araeolaimida is an order of marine free living nematodes.
References
Araeolaimidaat WoRMS
Nematode orders
{{chromadorea-stub ...
*
Ascaridida
*
Chromadorida
*
Desmodorida
*
Desmoscolecida
Desmoscolecida is an order of marine nematodes. In a worm of this order, the body tapers towards each end and is marked by a number of well-defined ridges. Their number varies in the different species. The head bears four movable setae, and some ...
*
Monhysterida
The Monhysterida are an order in the phylum Nematoda. Usually the stoma
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stem ...
*
Rhabditida
*
Rhigonematida
Notes
The
Benthimermithida are also occasionally placed here.
The Ascaridida appear to be nested within Rhabditida.
A part of the Nematoda phylum, one of the nine main phyla. Along with other certain species of roundworms.
Most frequently related to other main species of roundworms such as Earthworms, Pinworms, Hookworms, and Stongyloides.
References
External links
* (2002)
Nematoda Version of 2002-JAN-01. Retrieved 2008-NOV-02.
Protostome classes
{{Chromadorea-stub