Editing Protura (section)

== Morphology ==
Proturans have no eyes, wings, or antennae, and, lacking [[pigment]]ation, are usually whitish or pale brown. The sensory function of the absent antennae is fulfilled by the first pair of the three pairs of five-segmented [[arthropod leg|legs]], which are held up, pointing forward, and bearing numerous tarsal [[sensillum|sensilla]] and sensory hairs. They ambulate using the four rear legs.<ref name="Florida">{{cite web |url=http://entomology.ifas.ufl.edu/creatures/misc/proturans.htm |title=Proturans |author=Christopher Tipping |year=2004 |publisher=[[University of Florida]]}}</ref> The head is conical, and bears two [[pseudoculus|pseudoculi]] with unknown function. The body is elongated and cylindrical,<ref name="CSIRO">{{cite web |url=http://www.ento.csiro.au/education/hexapods/protura.html |title=Protura |publisher=[[Commonwealth Scientific and Industrial Research Organisation|CSIRO]]}}</ref> with a post-anal [[telson]] at the end. The [[Insect mouthparts|mouthparts]] are [[Entognatha|entognathous]] (enclosed within the head capsule) and consist of narrow [[Mandible (insect)|mandibles]] and maxillae.<ref name="Gullan" /> There are no [[cercus|cerci]] at the end of the abdomen, which gives the group their name, from the [[Greek language|Greek]] ''proto-'' (meaning "first", in this case implying primitive), and ''ura'', meaning "tail".<ref name="Carolina">{{cite web |url=http://www.cals.ncsu.edu/course/ent425/compendium/protura.html |title=Protura |date=March 5, 2005 |author=John R. Meyer |publisher=[[North Carolina State University]] |url-status=dead |archive-url=https://web.archive.org/web/20080515145323/http://www.cals.ncsu.edu/course/ent425/compendium/protura.html |archive-date=May 15, 2008 }}</ref> The first three abdominal segments bear short limb-like [[appendage]]s,<ref name="Florida" /> called "styli".<ref name="Carolina" /> The first pair of styli is two-segmented, while the second and third pair are either two-segmented or unsegmented.<ref name="galli" /> The [[Sex organ|genitalia]] are internal and the genital opening lies between the eleventh segment and the telson of the adult.<ref name="Florida" /> During mating, the genitalia of both sexes are everted from an abdominal chamber.<ref>{{cite book|page=184|title=Insect Morphology and Phylogeny |url=https://archive.org/details/insectmorphology0000beut |first1=Rolf G. |last1=Beutel|first2= Frank |last2=Friedrich|first3= Si-Qin|last3=Ge|first4=Xing-Ke|last4=Yang|isbn= 978-3-11-026263-6|publisher=De Gruyter|year=2014}}</ref> Only the two families [[Eosentomidae]] and [[Sinentomidae]] possess a simple [[Invertebrate trachea|tracheal]] system with a pair of [[Spiracle (arthropods)|spiracle]]s on both the [[mesothorax]] and the [[metathorax]], while proturans in the remaining families lack these structures and perform [[gas exchange]] by [[diffusion]].<ref name="Florida" /><ref>{{cite journal | pmc=6523364 | year=2019 | last1=Carapelli | first1=A. | last2=Bu | first2=Y. | last3=Chen | first3=W. J. | last4=Nardi | first4=F. | last5=Leo | first5=C. | last6=Frati | first6=F. | last7=Luan | first7=Y. X. | title=Going Deeper into High and Low Phylogenetic Relationships of Protura | journal=Genes | volume=10 | issue=4 | page=292 | doi=10.3390/genes10040292 | pmid=30974866 | doi-access=free }}</ref><ref>{{Cite book |last1=Resh |first1=Vincent H. |url=https://books.google.com/books?id=Jk0Hym1yF0cC&dq=Meso-+and+metathorax+are+the+only+body+segments+that+primarily+have+one+pair+of+spiracles+each&pg=PA857 |title=Encyclopedia of Insects |last2=Cardé |first2=Ring T. |date=2009-07-22 |publisher=Academic Press |isbn=978-0-08-092090-0 |language=en}}</ref>