Uniramia

clade|style=font-size:75%;line-height:75%
label1=Arthropoda
1=clade
label1=Uniramia
1=clade
1=Onychophora
2=Hexapoda
3=Myriapoda
2=Crustacea
3=Chelicerata
S. M. Manton's (1973) polyphyletic Arthropod hypothesis with Uniramia as one of three Phyla. [Manton, S. M. 1973. Arthropod phylogeny-a modern synthesis. J. Zool. 171:111-130.]

Uniramia was one of three phyla in the classification suggested by Sidnie Manton of the Arthropoda. This classification suggested that the arthropods were a polyphyletic group with three phyla and phylum Uniramia included the Hexapoda (insects), Myriapoda (centipedes and millipedes) and the Onychophora (velvetworms). The discovery of fossil lobopods that are intermediate between onychophorans and arthropods however led to the separation of the Lobopoda and Onychophora as a separate group. The name Uniramia thus became obsolete and was rejected as a polyphyletic group. The name Uniramia was later used for the Subphylum consisting of the insects + myriapods. The subphylum Uniramia was characterized by one pair of antennae and two pairs of mouthparts (single pairs of mandibles and maxillae). Their body forms and ecologies are diverse, though (in contrast to the crustaceans) most unirames are terrestrial. This group, however, is more unambiguosly named the Atelocerata (Heymons, 1901) and is the preferred name for the clade uniting the Hexapoda (insects) + Myriapoda.

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
Uniramia as a Subphylum [Brusca, R.C. & G.J. Brusca. 1990. Invertebrates, Sinauer.]

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

* [http://www.palaeos.com/Invertebrates/Arthropods/Uniramia.htm Paleos Metazoa: Arthropoda: Uniramia]
* [http://instruct1.cit.cornell.edu/courses/biog105/labs/inverts/arthropoda.html Bio 105-106 demo]

External links

* [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
* [http://www.palaeos.com/Invertebrates/Arthropods/Uniramia.htm "Uniramia"] at palaeos