Uniramia: Difference between revisions
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[[Image:Scolopendra_polymorpha_1.jpg|thumb|left|As members of [[Myriapoda]], centipedes like this ''[[Scolopendra polymorpha]]'' are part of subphylum Uniramia]] | [[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 | '''Uniramia''' (''uni'' – one, ''ramus'' – branch, i.e. single-branches) is formerly recognised group within [[Arthropod|Arthropoda]], now recognised as non-[[Monophyly|monophyletic]], united by their strictly [[uniramous]] (single branched) [[Appendage|appendages]].<ref name="Berkeley"/> | ||
[[Image:Onycophora_(515525252).jpg|thumb|left|Onychophora like this ''Peripatoides sp.'' are no longer counted as unirames.]] | [[Image:Onycophora_(515525252).jpg|thumb|left|Onychophora like this ''Peripatoides sp.'' are no longer counted as unirames.]] | ||
Uniramia | Uniramia was 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.<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> | ||
The name Uniramia was temporarily rejected as a polyphyletic group, but was later redefined to only include Myriapoda and Hexapoda. This subphylum Uniramia was considered to be characterized by their 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 | {{Cladogram | ||
Latest revision as of 00:37, 5 October 2025
Template:Short description Template:Cladogram
Uniramia (uni – one, ramus – branch, i.e. single-branches) is formerly recognised group within Arthropoda, now recognised as non-monophyletic, united by their strictly uniramous (single branched) appendages.[1]
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Uniramia was one of three subphyla in the Arthropoda classification suggested by Sidnie Manton. This classification divided arthropods into a three-phyla polyphyletic group, with phylum Uniramia including the Hexapoda (insects), Myriapoda (centipedes and millipedes) and the Onychophora (velvetworms). The discovery of fossil lobopods, determined to be intermediate between onychophorans and arthropods led to the splintering of the Lobopoda and Onychophora into separate groups.[1]
The name Uniramia was temporarily rejected as a polyphyletic group, but was later redefined to only include Myriapoda and Hexapoda. This subphylum Uniramia was considered to be characterized by their uniramous (single-branching) appendages, one pair of antennae and two pairs of mouthparts (single pairs of mandibles and maxillae). Their body forms and ecologies are diverse. While most unirames are terrestrial, "some are aquatic for part or all of their life cycles.[1]" 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,[2] be an infraphylum beneath Mandibulata,[3] or may no longer be a valid category after closer, cladistics-based genetic study.[4]
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
References
External links
- A Cladistic Analysis of Arthropoda: Examining the Evolution of Biramous Appendages and Mandibles, Katherine McBride, Lindsey Moll, Whitney Zurat, Susquehanna University
- Uniramia at palaeos