Editing Flea (section)

== Taxonomy and phylogeny ==
=== History ===
Between 1735 and 1758, the Swedish naturalist [[Carl Linnaeus]] first classified insects, doing so on the basis of their wing structure. One of the seven orders into which he divided them was "Aptera", meaning wingless, a group in which as well as fleas, he included [[spider]]s, [[woodlice]] and [[myriapod]]s. It wasn't until 1810 that the French zoologist [[Pierre André Latreille]] reclassified the insects on the basis of their mouthparts as well as their wings, splitting Aptera into [[Thysanura]] (silverfish), [[Anoplura]] (sucking lice) and Siphonaptera (fleas), at the same time separating off the arachnids and [[crustacean]]s into their own subphyla.<ref name=Gillott>{{cite book|author=Gillott, Cedric|title=Entomology |url=https://books.google.com/books?id=latCAAAAQBAJ&pg=PA97 |year=2005|publisher=Springer Science & Business Media|isbn=978-1-4020-3183-0|page=97}}</ref> The group's name, Siphonaptera, is zoological Latin from the Greek ''siphon'' (a tube) and ''aptera'' (wingless).<ref>{{cite web|last1=Meyer|first1=John R.|title=Siphonaptera|url=https://projects.ncsu.edu/cals/course/ent425/library/compendium/siphonaptera.html|publisher=North Carolina State University|access-date=3 December 2016|date=28 March 2016|archive-date=25 September 2022|archive-url=https://web.archive.org/web/20220925114314/https://projects.ncsu.edu/cals/course/ent425/library/compendium/siphonaptera.html|url-status=dead}}</ref>

=== External phylogeny ===
It was historically unclear whether the Siphonaptera are sister to the [[Mecoptera]] (scorpionflies and allies), or are inside that clade, making "Mecoptera" paraphyletic. The earlier suggestion that the Siphonaptera are sister to the [[Boreidae]] (snow scorpionflies)<ref name=Whiting2008>{{cite journal |last1=Whiting |first1=Michael F. |author1-link=Michael F. Whiting|last2=Whiting |first2=Alison S. |last3=Hastriter |first3=Michael W. |last4=Dittmar |first4=Katharina |title=A molecular phylogeny of fleas (Insecta: Siphonaptera): origins and host associations |journal=Cladistics |date=2008 |volume=24 |issue=5 |pages=677–707 |doi=10.1111/j.1096-0031.2008.00211.x |citeseerx=10.1.1.731.5211  |s2cid=33808144 }}</ref><ref name=Whiting2002>{{cite journal |last1=Whiting |first1=Michael F. |author1-link=Michael F. Whiting|year=2002 |title=Mecoptera is paraphyletic: multiple genes and phylogeny of Mecoptera and Siphonaptera |journal=Zoologica Scripta |volume=31 |issue=1 |pages=93–104 |url=http://www3.interscience.wiley.com/journal/118916123/abstract |archive-url=https://archive.today/20130105095659/http://www3.interscience.wiley.com/journal/118916123/abstract |url-status=dead |archive-date=2013-01-05 |doi=10.1046/j.0300-3256.2001.00095.x |s2cid=56100681 }}</ref><ref name=WiegmannYates2012>{{cite book |last1=Wiegmann |first1=Brian |last2=Yeates |first2=David K. |title=The Evolutionary Biology of Flies |url=https://books.google.com/books?id=rElP5sNn6IYC&pg=PA5 |year=2012 |publisher=Columbia University Press |isbn=978-0-231-50170-5 |page=5 |quote=Recently, a close affinity between Siphonaptera and Mecoptera has been convincingly demonstrated via morphology (Bilinski et al. 1998) and molecular data (Whiting 2002), rendering Mecoptera paraphyletic, but making the clade including Mecoptera and Siphonaptera monophyletic}}</ref> is not supported. A 2020 genetic study recovered Siphonaptera within Mecoptera, with strong support, as the sister group to [[Nannochoristidae]], a small, [[Relict (biology)|relictual]] group of mecopterans native to the Southern Hemisphere. Fleas and nannochoristids share several similarities with each other that are not shared with other mecopterans, including similar mouthparts as well as a similar sperm pump organisation.<ref name=":0">{{Cite journal|last1=Tihelka|first1=Erik|last2=Giacomelli|first2=Mattia|last3=Huang|first3=Di-Ying|last4=Pisani|first4=Davide|last5=Donoghue|first5=Philip C. J.|last6=Cai|first6=Chen-Yang|date=2020-12-21|title=Fleas are parasitic scorpionflies|url=https://www.mapress.com/pe/article/view/palaeoentomology.3.6.16|journal=Palaeoentomology|language=en|volume=3|issue=6|pages=641–653–641–653|doi=10.11646/palaeoentomology.3.6.16|issn=2624-2834|hdl=1983/8d3c12c6-529c-4754-b59d-3abf88a32fc9|s2cid=234423213|hdl-access=free}}</ref>

Relationships of Siphonaptera per Tihelka et al. 2020.<ref name=":0" />

{{clade|{{clade 
   |1=[[Diptera]] (true flies) [[File:Common house fly, Musca domestica.jpg|70px]] 
   |2={{clade
      |1=[[Boreidae]] (snow scorpionflies, 30 spp.) [[File:Boreus hiemalis2 detail.jpg|85px]]
      |2={{clade
         |1={{clade
            |1=[[Nannochoristidae]] (southern scorpionflies, 8 spp.) <!--NC img http://v3.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=892130-->
            |2='''Siphonaptera''' (fleas, 2500 spp.) [[File:British Entomologycutted Plate114.png|50px]]
            }}
         |2=[[Pistillifera]] (scorpionflies, hangingflies, 400 [[Species|spp]].) [[File:Gunzesrieder Tal Insekt 3.jpg|90px]] 
         }}
      }}
   }}|label1=[[Antliophora]]}}

=== Fossil history ===
[[File:Flea in amber.jpg|thumb|upright|[[Cenozoic]] flea in [[amber]], c. 20 [[mya (unit)|mya]], is morphologically modern.]]
[[File:P.wangi fossil image.png|thumb|''[[Pseudopulex|Pseudopulex wangi]]'', a primitive flea from the Early Cretaceous of China]]

Fleas likely descended from [[scorpionflies]], insects that are predators or scavengers.<ref name=":0" /> Fossils of large, wingless [[stem-group]] fleas with siphonate (sucking) mouthparts from the Middle [[Jurassic]]<ref>{{cite journal |author=Huang, D. |author2=Engel, M.S. |author3=Cai, C. |author4=Wu, H. |author5=Nel, A. |date=8 March 2012 |title=Diverse transitional giant fleas from the Mesozoic era of China |journal=Nature |volume=483 |issue=7388 |pages=201–204 |doi=10.1038/nature10839 |pmid=22388812|bibcode=2012Natur.483..201H |s2cid=4415855 }}</ref> to Early [[Cretaceous]] have been found in northeastern China and Russia, belonging to the families [[Saurophthiridae]] and [[Pseudopulicidae]], as well as ''[[Tarwinia]]'' from the Early Cretaceous of Australia. Most flea families formed after the end of the Cretaceous (in the [[Paleogene]] and onwards). Modern fleas probably arose in the southern continental area of [[Gondwana]], and migrated rapidly northwards from there. They most likely evolved with [[mammal]] hosts, only later moving to [[bird]]s.<ref>{{cite journal |last1=Zhu |first1=Qiyun |last2=Hastriter |first2=Michael |last3=Whiting |first3=Michael |last4=Dittmar |first4=Katherina |title=Fleas (Siphonaptera) are Cretaceous, and Evolved with Theria |journal=Molecular Phylogenetics and Evolution |date=September 2015 |volume=90 |pages=129–139 |biorxiv=10.1101/014308 |doi=10.1016/j.ympev.2015.04.027 |pmid=25987528|bibcode=2015MolPE..90..129Z |s2cid=13433327 }}</ref>

Siphonaptera is a relatively small order of insects: members of the order undergo complete metamorphosis and are secondarily wingless (their ancestors had wings which modern forms have lost). In 2005, Medvedev listed 2005 species in 242 genera, and despite subsequent descriptions of new species, bringing the total up to around 2500 species,<ref name=Whiting2008/> this is the most complete database available. The order is divided into four infraorders and eighteen families. Some families are exclusive to a single host group; these include the Malacopsyllidae ([[armadillo]]s), Ischnopsyllidae ([[bat]]s) and Chimaeropsyllidae ([[elephant shrew]]s).<ref name=Krasnov3>{{cite book|author=Krasnov, Boris R. |title=Functional and Evolutionary Ecology of Fleas: A Model for Ecological Parasitology |url=https://books.google.com/books?id=tkvr8h8zxFwC&pg=PA3 |year=2008 |publisher=Cambridge University Press |isbn=978-1-139-47266-1 |pages=3–9}}</ref>

Many of the known species are little studied. Some 600 species (a quarter of the total) are known from single records. Over 94% of species are associated with [[mammal]]ian hosts, and only about 3% of species can be considered to be specific parasites of [[bird]]s. The fleas on birds are thought to have originated from mammalian fleas; at least sixteen separate groups of fleas switched to avian hosts during the evolutionary history of the Siphonaptera. Occurrences of fleas on reptiles is accidental, and fleas have been known to feed on the [[hemolymph]] (bloodlike body fluid) of [[tick]]s.<ref name=Krasnov3/>

=== Internal phylogeny ===
Flea phylogeny was long neglected, the discovery of [[Homology (biology)|homologies]] with the parts of other insects being made difficult by their extreme specialization. Whiting and colleagues prepared a detailed molecular phylogeny in 2008, with the basic structure shown in the cladogram. The [[Hectopsyllidae]], including the harmful [[Tunga penetrans|chigoe flea or jigger]], is sister to the rest of the Siphonaptera.<ref name=Whiting2008/>

{{clade
|label1='''Siphonaptera'''
|1={{clade
   |1=[[Hectopsyllidae]] (inc. [[Tunga penetrans|jigger]]) [[File:ChiggerBMNH (cropped).jpg|75px]]
   |2=<!--9-->{{clade
      |1=<!--10-->{{clade
         |1=<!--11-->{{clade
            |1=[[Pygiopsyllomorpha]]
            |2={{clade
               |1=[[Macropsyllidae]], [[Coptopsyllidae]]
               |2=[[Neotyphloceratini]], [[Ctenophthalmini]], [[Doratopsyllinae]]
               }}
            }}
         |2=<!--26-->{{clade
            |1=[[Stephanocircidae]] [[File:Craneopsylla minerva.jpg|75px]]
            |2=clade inc. [[Rhopalopsyllidae]], [[Ctenophthalmidae]], [[Hystrichopsyllidae]] [[File:British Entomologycutted Plate114.png|75px]]
            }}
         }}
      |2={{clade
         |1={{clade
            |1=[[Chimaeropsyllidae]]
            |2=[[Pulicidae]] (inc. the [[cat flea]], vector of [[bubonic plague]]) [[File:NHMUK010177265 The plague flea - Xenopsylla cheopis cheopis (Rothschild, 1903).jpg|75px]]
            }}
         |2=[[Ceratophyllomorpha]] (inc. the [[Ceratophyllidae]], such as the widespread [[moorhen flea]]) [[File:NHMUK010177289 The moorhen flea - Dasypsyllus Dasypsyllus gallinulae gallinulae (Dale, 1878).jpg|75px]]
         }}
      }}
   }}
}}