Editing Louse (section)

==Classification==
Lice are classified as an [[infraorder]] called Phthiraptera, named by [[Ernst Haeckel]] in 1896. Phthiraptera was previously recognized as an [[order (biology)|order]], and was considered the [[sister taxon]] to the order [[Psocoptera]], which contains booklice, barklice and barkflies, all within the greater group called [[Psocodea]]. However, a 2021 genetic study determined that Phthiraptera lice are a highly modified lineage within the Psocoptera group, thus rendering Psocoptera [[paraphyletic]] and necessating a classification change. Phthiraptera is now nested within the [[suborder]] [[Troctomorpha]], belonging to the now-ranked order [[Psocodea]].<ref name="deMoya2021">{{Cite journal|last1=de Moya|first1=Robert S|last2=Yoshizawa|first2=Kazunori|last3=Walden|first3=Kimberly K O|last4=Sweet|first4=Andrew D|last5=Dietrich|first5=Christopher H|last6=Kevin P|first6=Johnson|date=2021-06-16|editor-last=Buckley|editor-first=Thomas|title=Phylogenomics of Parasitic and Nonparasitic Lice (Insecta: Psocodea): Combining Sequence Data and Exploring Compositional Bias Solutions in Next Generation Data Sets|url=https://academic.oup.com/sysbio/article/70/4/719/5912026|journal=Systematic Biology|language=en|volume=70|issue=4|pages=719–738|doi=10.1093/sysbio/syaa075|pmid=32979270|issn=1063-5157|doi-access=free}}</ref><ref name="PsocodeaSpeciesFile">{{Cite web| website = Psocodea Species File |title = Anoplura Leach, 1815 |last1 = Hopkins |first1 = H. |last2 = Johnson |first2 = K. P. |last3 = Smith |first3 = V. S. |url = https://psocodea.speciesfile.org/otus/878997/overview |access-date = 12 May 2025 }}</ref> Within Psocodea, the Phthiraptera lice are most closely related to [[family (biology)|family]] [[Liposcelididae]].<ref>{{cite journal | vauthors = Light JE, Smith VS, Allen JM, Durden LA, Reed DL | title = Evolutionary history of mammalian sucking lice (Phthiraptera: Anoplura) | journal = BMC Evolutionary Biology | volume = 10 | issue = 1 | pages = 292 | date = September 2010 | pmid = 20860811 | pmc = 2949877 | doi = 10.1186/1471-2148-10-292 | doi-access = free | bibcode = 2010BMCEE..10..292L }}</ref>

A [[cladogram]] showing the position of Phthiraptera within [[Psocodea]] is shown below:<ref name="deMoya2021"/>
{{clade| style=font-size:85%; line-height:100%
 |label1='''[[Psocodea]]'''
 |1={{clade
  |1={{clade
   |label1=[[Troctomorpha]]
   |1={{clade
    |1={{clade
     |1={{clade
      |label1='''Phthiraptera'''
      |1={{clade
       |1={{clade
        |1=[[Philopteridae]]
        |2={{clade
         |1={{clade
          |1=[[Anoplura]]
          |2=[[Rhynchophthirina]] }}
         |2=[[Trichodectidae]] }} }}
       |2=[[Amblycera]] }}
      |2=[[Liposcelididae]] }}
     |2={{clade
      |1=[[Pachytroctidae]]
      |2=[[Sphaeropsocidae]] }} }}
    |2=[[Amphientometae]] }}
   |label2=[[Psocomorpha]]
   |2={{clade
    |1={{clade
     |1={{clade
      |1=[[Homilopsocidea]]
      |2=[[Caeciliusetae]] }}
     |2={{clade
      |1={{clade
       |1=[[Psocetae]]
       |2=[[Epipsocetae]] }}
      |2=[[Philotarsetae]] }} }}
    |2=[[Archipsocetae]] }} }}
  |label2=[[Trogiomorpha]]
  |2={{clade
   |1={{clade
    |1=[[Atropetae]]
    |2=[[Psyllipsocetae]] }}
   |2=[[Prionoglaridetae]] ([[paraphyletic]]) }} }} }}

===Internal classification===
Phthiraptera is clearly a [[monophyletic]] grouping, united as the members are by a number of derived features, including their parasitism on [[warm-blooded]] vertebrates and the combination of their [[Metathorax|metathoracic]] [[ganglia]] with their [[abdominal]] ganglia to form a single ventral nerve junction.<ref name=Ax>{{cite book| vauthors = Ax P |title=Multicellular Animals: Volume II: The Phylogenetic System of the Metazoa |url=https://books.google.com/books?id=x7vtCAAAQBAJ&pg=PA303 |year=2013|publisher=Springer Science & Business Media |isbn=978-3-662-10396-8 |pages=303–307 }}</ref>

The order has traditionally been divided into two suborders, the sucking lice ([[Anoplura]]) and the chewing lice ([[Mallophaga]]). However, subsequent classifications indicated that the Mallophaga are [[paraphyletic]], and four suborders were then recognized.<ref name=info>{{cite web |url=http://phthiraptera.info/ |title=Phthiraptera.info | vauthors = Smith V |publisher=International Society of Phthirapterists |access-date=25 October 2015}}</ref>

Upon finding that Phthiraptera was nested within [[Psocoptera]] in 2021, de Moya ''et al.'' reduced the rank of Phthiraptera to [[infraorder]], and the [[suborder]]s were reduced down to [[parvorder]].<ref name="deMoya2021"/><ref name="PsocodeaSpeciesFile"/> Also, based on the [[paraphyletic]] nature of one of the parvorders -  [[Ischnocera]] - they proposed creation of a fifth parvorder [[Trichodectera]] to be created and split off from Ischnocera. Here are the five proposed parvorders within Phthiraptera:<ref name="deMoya2021"/>
* [[Amblycera]]: primitive chewing lice, widespread on birds, and also occurring on South American and Australian mammals
* [[Anoplura]]: sucking lice, occurring on mammals exclusively
* [[Rhynchophthirina]]: parasites of elephants and [[warthog]]s
* [[Ischnocera]]: avian chewing lice, and contains the large family [[Philopteridae]]
* [[Trichodectera]]: parasitizing mammals, split off from Ischnocera, and contains the family [[Trichodectidae]]

===Evolutionary history===
The oldest confirmed fossil louse is ''[[Archimenopon myanmarensis]]'', an [[amblycera]]n from the Cretaceous amber from [[Myanmar]].<ref name=Archimenopon /> Another early representative of the group is a bird louse, ''[[Megamenopon rasnitsyni]]'', from [[Eckfelder Maar]], Germany, which dates to the [[Eocene]], around 44 million years ago.<ref name="Scratching an ancient itch: an Eoce">{{cite journal | vauthors = Wappler T, Smith VS, Dalgleish RC | title = Scratching an ancient itch: an Eocene bird louse fossil | journal = Proceedings. Biological Sciences | volume = 271 Suppl 5 | issue = suppl_5 | pages = S255-8 | date = August 2004 | pmid = 15503987 | pmc = 1810061 | doi = 10.1098/rsbl.2003.0158 }}</ref> ''[[Saurodectes vrsanskyi]]'' from the Early Cretaceous ([[Aptian]]) [[Zaza Formation]] of [[Buryatia]], Russia, has also been suggested to be a louse, but this is tentative.<ref>{{cite journal | vauthors = Rasnitsyn AP, Zherikhin VV | title = First fossil chewing louse from the lower Cretaceous of Baissa, Transbaikalia (Insecta, Pediculida= Phthiriaptera, Saurodectidae fam. n.). | journal = Russian Entomological Journal | date = 1999 | volume = 8 | issue = 4 | pages = 253–5 }}</ref>

Placental mammal lice had a single common ancestor that lived on [[Afrotheria]] with this arising from host-switching from an ancient avian host.<ref name="p273">{{cite journal |last1=Johnson |first1=Kevin P. |last2=Matthee |first2=Conrad |last3=Doña |first3=Jorge |date=2022 |title=Phylogenomics reveals the origin of mammal lice out of Afrotheria |journal=Nature Ecology & Evolution |volume=6 |issue=8 |pages=1205–1210 |doi=10.1038/s41559-022-01803-1 |pmid=35788706 |bibcode=2022NatEE...6.1205J |issn=2397-334X}}</ref>