Editing Uniramia

{{Short description|Group of arthropods}}
{{Cladogram|
|caption=S. M. Manton's (1973) polyphyletic arthropod hypothesis with Uniramia as one of three subphyla.<ref>Manton, S. M. 1973. Arthropod phylogeny-a modern synthesis. J. Zool. 171:111–130.</ref>
|clades={{Clade
|label1=Arthropoda
|1={{clade
|label1=Uniramia
|1={{clade
   |1=[[Onychophora]]
   |2=[[Hexapoda]]
   |3=[[Myriapoda]]
   }}
|2=[[Crustacea]]
|3=[[Chelicerata]]
}}
}}
}}
[[Image:Scolopendra_polymorpha_1.jpg|thumb|left|As members of [[Myriapoda]], centipedes like this ''[[Scolopendra polymorpha]]'' are part of subphylum Uniramia]]
'''Uniramia''' (''uni'' – one, ''ramus'' – branch, i.e. single-branches) is a group within the [[arthropod]]s. In the past this group included the [[Onychophora]], which are now considered a separate category. The group is currently used in a narrower sense.<ref name="Berkeley"/>
[[Image:Onycophora_(515525252).jpg|thumb|left|Onychophora like this ''Peripatoides sp.'' are no longer counted as unirames.]]

Uniramia is one of three [[subphylum|subphyla]] in the [[Arthropoda]] classification suggested by [[Sidnie Manton]]. This classification divided arthropods into a three-phyla  [[polyphyly|polyphyletic]] group, with phylum Uniramia including the [[Hexapoda]] (insects), [[Myriapoda]] (centipedes and millipedes) and the [[Onychophora]] (velvetworms). The discovery of [[fossil]] [[Lobopodia|lobopods]], determined to be intermediate between onychophorans and arthropods led to the splintering of the [[Lobopodia|Lobopoda]] and Onychophora into separate groups.  This redefined the Uniramia as strictly "true" arthropods with exoskeletons and jointed appendages. Uniramians have strictly [[uniramous]] appendages.<ref name="Berkeley">{{cite web |url=http://www.ucmp.berkeley.edu/arthropoda/uniramia/uniramia.html |title=Introduction to the Uniramia |publisher=[[University of California, Berkeley]] |access-date=October 1, 2010}}</ref>

[[Systematics]] can result in rival taxonomies, and this seems to have happened to Uniramia. The name Uniramia was temporarily rejected as a polyphyletic group, but when used now refers to the subphylum consisting of the insects + myriapods. Subphylum Uniramia is characterized by uniramous (single-branching) appendages, one pair of antennae and two pairs of mouthparts (single pairs of [[Mandible (arthropod mouthpart)|mandibles]] and [[Maxilla (arthropod mouthpart)|maxillae]]). Their body forms and ecologies are diverse. While most unirames are terrestrial, "some are aquatic for part or all of their life cycles.<ref name="Berkeley"/>" [[Atelocerata]] is described as replacing Uniramia in early twentieth-century texts (Heymons, 1901), where it was the preferred name for the category uniting the [[Hexapoda]] (insects) + [[Myriapoda]]; but depending on the source, the term Atelocerata may have replaced [[Mandibulata]],<ref>{{cite web |url=http://biology.clc.uc.edu/Courses/bio106/arthrpod.htm |title=Phylum Arthropoda |access-date=2009-06-24 |url-status=dead |archive-url=https://web.archive.org/web/20090224111249/http://biology.clc.uc.edu/Courses/bio106/arthrpod.htm |archive-date=2009-02-24 }}</ref> be an infraphylum beneath Mandibulata,<ref>{{cite web|url=http://zipcodezoo.com/Key/Animalia/atelocerata_Infraphylum.asp |title=Atelocerata (Infraphylum) |access-date=June 24, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090625032306/http://zipcodezoo.com/Key/Animalia/Atelocerata_Infraphylum.asp |archive-date=June 25, 2009 }}</ref> or may no longer be a valid category after closer, [[cladistics]]-based genetic study.<ref>{{Cite web|url=http://www.faqs.org/abstracts/Zoology-and-wildlife-conservation/Demise-of-the-Atelocerata-Homeotic-genes-and-the-evolution-of-arthropods-and-chordates.html|title = Demise of the Atelocerata? Homeotic genes and the evolution of arthropods and chordates. The case of the velvet worm}}</ref>

{{Cladogram
|caption=Uniramia as a Subphylum<ref>Brusca, R.C. & G.J. Brusca. 1990. Invertebrates, Sinauer.</ref>
|clades={{clade|style=font-size:75%;line-height:75%
|1={{clade
   |label1=[[Chelicerata]]
   |1={{clade
      |1={{clade
         |1=[[Arachnida]]
	 |2=[[Merostomata]]
         }}
      |2=[[Pycnogonida]]
      }}
   }}
|2={{clade
   |1=[[Trilobitomorpha]]
   |2={{clade
      |label1=Uniramia
      |1={{clade
         |label1=[[Myriapoda]]
	 |1={{clade
	    |1={{clade
	       |1=[[Symphyla]]
	       |2=[[Chilopoda]]
	       }}
	    |2=[[Diplopoda]]
	    }}
	 |label2=[[Hexapoda]]
	 |2={{clade
	    |1=[[Entognatha]]
	    |2=[[Ectognatha]]
	    }}
         }}
      |2=[[Crustacea]]
      }}
   }}
}}
}}

The [[Crustacea]] were generally considered the closest relatives of the Uniramia, and sometimes these were united as [[Mandibulata]]. However, the competing hypothesis — that Crustacea and Hexapoda form a monophyletic group, the [[Pancrustacea]], to which the Myriapoda are the closest relatives — has support from molecular and fossil evidence.

==Notes==
{{reflist}}

==References==
* [https://web.archive.org/web/20051111173402/http://palaeos.com/Invertebrates/Arthropods/Uniramia.htm Paleos Metazoa: Arthropoda: Uniramia]
* [https://web.archive.org/web/20070310222103/http://instruct1.cit.cornell.edu/courses/biog105/labs/inverts/arthropoda.html Bio 105–106 demo]

==External links==
* [https://web.archive.org/web/20070301212542/http://www.susqu.edu/students/m/mcbride/The%20Zebras%20mandible%203pub.htm ''A Cladistic Analysis of Arthropoda:  Examining the Evolution of Biramous Appendages and Mandibles''], Katherine McBride, Lindsey Moll, Whitney Zurat, Susquehanna University
* [https://web.archive.org/web/20051111173402/http://palaeos.com/Invertebrates/Arthropods/Uniramia.htm ''Uniramia''] at palaeos

[[Category:Arthropod taxonomy]]
[[Category:Animal subphyla]]