Editing Millipede (section)

==Classification==
[[File:Millipede order species comparison.png|thumb|left|alt=Diversity|Approximate relative diversity of [[Extant taxon|extant]] millipede orders, ranging from ca. 3,500 species of [[Polydesmida]] to 2 species of [[Siphoniulida]]<ref name="Shear 2011 class."/>]]
Approximately 12,000 millipede [[species]] have been described. Estimates of the true number of species on earth range from 15,000<ref name="Brewer et al 2012 PLOS"/> to as high as 80,000.<ref name=SierwaldBond2007>{{cite journal |last1=Sierwald |first1=Petra |last2=Bond |first2=Jason E. |title=Current status of the myriapod class Diplopoda (Millipedes): Taxonomic diversity and phylogeny |journal=[[Annual Review of Entomology]] |year=2007 |volume=52 |issue=1 |pages=401–420 |doi=10.1146/annurev.ento.52.111805.090210 |pmid=17163800}}</ref> Few species of millipede are at all widespread; they have very poor dispersal abilities, depending as they do on terrestrial locomotion and humid habitats. These factors have favoured genetic isolation and rapid [[speciation]], producing many lineages with restricted ranges.<ref name=Barker>{{cite book|author=Barker, G.M.|title=Natural Enemies of Terrestrial Molluscs|url=https://books.google.com/books?id=bjAh_Gszsy8C&pg=PA405 |year=2004 |publisher=CABI |isbn=978-0-85199-061-3 |pages=405–406}}</ref>

The living members of the Diplopoda are divided into sixteen orders in two subclasses.<ref name="Shear 2011 class.">{{cite journal |last=Shear |first=W. |author-link=William Shear |year=2011 |title=Class Diplopoda de Blainville in Gervais, 1844. In: Zhang, Z.-Q. (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness |url=http://www.mapress.com/zootaxa/2011/f/zt03148p164.pdf |url-status=live |journal=[[Zootaxa]] |volume=3148 |pages=159–164 |doi=10.11646/zootaxa.3148.1.32 |archive-url=https://web.archive.org/web/20190725010639/https://www.mapress.com/zootaxa/2011/f/zt03148p164.pdf |archive-date=2019-07-25 |access-date=2013-10-14}}</ref> The basal subclass Penicillata contains a single order, Polyxenida (bristle millipedes).<ref>{{Cite web |title=Bristle Millipedes (Subclass Penicillata) |url=https://www.inaturalist.org/taxa/372767-Penicillata |access-date=2023-03-07 |website=iNaturalist |language=en}}</ref> All other millipedes belong to the subclass Chilognatha consisting of two infraclasses: Pentazonia, containing the short-bodied pill millipedes, and Helminthomorpha (worm-like millipedes), containing the great majority of the species.<ref name="core.ecu.edu">{{cite book |chapter=Diplopoda |last1=Bueno-Villegas |first1=Julián |last2=Sierwald |first2=Petra |last3=Bond |first3=Jason E. |editor1-last=Bousquets |editor1-first=J. L. |editor2-last=Morrone |editor2-first=J. J. |title=Biodiversidad, taxonomia y biogeografia de artropodos de Mexico |pages=569–599 |chapter-url=http://www.biodiversidad.gob.mx/publicaciones/librosDig/pdf/Artropodos%20IV_7.pdf |access-date=2016-12-18 |archive-date=2016-12-20 |archive-url=https://web.archive.org/web/20161220184814/http://www.biodiversidad.gob.mx/publicaciones/librosDig/pdf/Artropodos%20IV_7.pdf |url-status=live }}</ref><ref name="Shelley">{{cite web |last=Shelley |first=Rowland M. |title=Millipedes |publisher=University of Tennessee: Entomology and Plant Pathology |url=https://ag.tennessee.edu/EPP/Pages/Nadiplochilo/Millipedes.aspx |access-date=17 July 2016 |archive-date=16 August 2016 |archive-url=https://web.archive.org/web/20160816012404/https://ag.tennessee.edu/EPP/Pages/Nadiplochilo/Millipedes.aspx |url-status=live }}</ref>

===Outline of classification===
{{Details|List of millipede families}}
The higher-level classification of millipedes is presented below, based on Shear, 2011,<ref name="Shear 2011 class." /> and Shear & Edgecombe, 2010<ref name=Shear.Edgecombe2010/> (extinct groups). Recent cladistic and molecular studies have challenged the traditional classification schemes above, and in particular the position of the orders Siphoniulida and Polyzoniida is not yet well established.<ref name=SierwaldBond2007 /> The placement and positions of extinct groups (†) known only from fossils is tentative and not fully resolved.<ref name="SierwaldBond2007" /><ref name="Shear.Edgecombe2010">{{cite journal |last1=Shear |first1=William A. |author-link=William Shear |last2=Edgecombe |first2=Gregory D. |year=2010 |title=The geological record and phylogeny of the Myriapoda |journal=Arthropod Structure & Development |volume=39 |issue=2–3 |pages=174–190 |doi=10.1016/j.asd.2009.11.002 |pmid=19944188|bibcode=2010ArtSD..39..174S }}</ref> After each name is listed the [[author citation (zoology)|author citation]]: the name of the person who coined the name or defined the group, even if not at the current rank.

'''Class Diplopoda''' <small>de Blainville in Gervais, 1844</small>
* Subclass [[Penicillata]] <small>Latreille, 1831</small>
** Order [[Polyxenida]] <small>Verhoeff, 1934</small>
* Subclass †[[Arthropleuridea]] (placed in Penicillata by some authors)<ref name=Shear.Edgecombe2010 />
**Order †[[Arthropleurida]] <small>Waterlot, 1934</small>
** Order †[[Eoarthropleurida]] <small>Shear & Selden, 1995</small>
** Order †[[Microdecemplicida]] <small>Wilson & Shear, 2000</small>
* Subclass Chilognatha <small>Latreille, 1802</small>
** Order †[[Zosterogrammida]] <small>Wilson, 2005</small> (Chilognatha ''[[incertae sedis]]'')<ref name=Shear.Edgecombe2010 />
** Infraclass [[Pentazonia]] <small>Brandt, 1833 </small>
*** Order †[[Amynilyspedida]] <small>Hoffman, 1969</small>
*** Superorder [[Limacomorpha]] <small>Pocock, 1894 </small>
**** Order [[Glomeridesmida]] <small>Cook, 1895 </small>
*** Superorder [[Oniscomorpha]] <small>Pocock, 1887 </small>
**** Order [[Glomerida]] <small>Brandt, 1833 </small>
**** Order [[Sphaerotheriida]] <small>Brandt, 1833</small>
** Infraclass Helminthomorpha <small>Pocock, 1887</small>
*** Superorder †[[Archipolypoda]] <small>Scudder, 1882</small>
**** Order †[[Archipolypoda|Archidesmida]] <small>Wilson & Anderson 2004</small>
**** Order †[[Cowiedesmida]] <small>Wilson & Anderson 2004</small>
**** Order †[[Euphoberiida]] <small>Hoffman, 1969</small>
**** Order †[[Palaeosomatida]] <small>Hannibal & Krzeminski, 2005</small>
*** Order †[[Pleurojulida]] <small>Schneider & Werneburg, 1998</small> (possibly sister to Colobognatha)<ref name=SierwaldBond2007/>
*** Subterclass [[Colobognatha]] <small>Brandt, 1834 </small>
**** Order [[Platydesmida]] <small>Cook, 1895</small>
**** Order [[Polyzoniida]] <small>Cook, 1895 </small>
**** Order [[Siphonocryptida]] <small>Cook, 1895</small>
**** Order [[Siphonophorida]] <small>Newport, 1844</small>
*** Subterclass Eugnatha <small>Attems, 1898</small>
**** Superorder Juliformia <small>Attems, 1926</small>
***** Order [[Julida]] <small>Brandt, 1833</small>
***** Order [[Spirobolida]] <small>Cook, 1895</small>
***** Order [[Spirostreptida]] <small>Brandt, 1833</small>
*****Superfamily †[[Xyloiuloidea]] <small>Cook, 1895</small> (Sometimes aligned with Spirobolida)<ref name=Hoffman1963>{{cite journal|last=Hoffman|first=R. L.|title=New genera and species of Upper Paleozoic Diplopoda|journal=[[Journal of Paleontology]]|year=1963|volume=37|issue=1|pages=167–174|jstor=1301419}}</ref>
**** Superorder Nematophora <small>Verhoeff, 1913 </small>
***** Order [[Callipodida]] <small>Pocock, 1894</small>
***** Order [[Chordeumatida]] <small>Pocock 1894</small>
***** Order [[Stemmiulida]] <small>Cook, 1895</small>
***** Order [[Siphoniulida]] <small>Cook, 1895</small>
**** Superorder Merocheta <small>Cook, 1895</small>
***** Order [[Polydesmida]] <small>Pocock, 1887</small>

===Evolution===
Millipedes are among the first animals to have [[Colonization of the land|colonised land]] during the [[Silurian|Silurian period]].<ref name="Garwood">{{cite journal|last1=Garwood |first1=Russell |last2=Edgecombe |first2=Gregory |year=2011 |title=''Early terrestrial animals, evolution and uncertainty'' |journal=Evolution: Education and Outreach |volume=4 |issue=3 |pages=489–501 |doi=10.1007/s12052-011-0357-y |doi-access=free }}</ref> Early forms probably ate [[moss]]es and primitive [[vascular plant]]s. There are two major groups of millipedes whose members are all extinct: the [[Archipolypoda]] ("ancient, many-legged ones") which contain the oldest known terrestrial animals, and [[Arthropleuridea]], which contain the largest known land invertebrates. ''[[Pneumodesmus newmani]]'' is the earliest member of the millipedes from the late [[Wenlock epoch]] of the late [[Silurian]] around {{Ma|428}},<ref name=wellman23>{{cite journal|first1=C.H.|last1=Wellman|first2=G.|last2=Lopes|first3=Z.|last3=McKellar|first4=A.|last4=Hartley|year=2023|title=Age of the basal 'Lower Old Red Sandstone' Stonehaven Group of Scotland: The oldest reported air-breathing land animal is Silurian (late Wenlock) in age|journal=Journal of the Geological Society|volume=181 |publisher=The Geological Society of London|doi=10.1144/jgs2023-138|issn=0016-7649|doi-access=free|hdl=2164/22754|hdl-access=free}}</ref><ref name="Wilson&Anderson2004"/> or early [[Lochkovian]] of the early [[Devonian]] around 414 million years ago,<ref>{{Cite journal |last1=Suarez |first1=Stephanie E. |last2=Brookfield |first2=Michael E. |last3=Catlos |first3=Elizabeth J. |last4=Stöckli |first4=Daniel F. |date=2017-06-28 |title=A U-Pb zircon age constraint on the oldest-recorded air-breathing land animal |journal=PLOS ONE |volume=12 |issue=6 |pages=e0179262 |doi=10.1371/journal.pone.0179262 |doi-access=free |issn=1932-6203 |pmc=5489152 |pmid=28658320|bibcode=2017PLoSO..1279262S }}</ref><ref>{{Cite journal |last1=Brookfield |first1=M. E. |last2=Catlos |first2=E. J. |last3=Garza |first3=H. |date=2024-07-07 |title=The oldest 'millipede'-plant association? Age, paleoenvironments and sources of the Silurian lake sediments at Kerrera, Argyll and Bute, Scotland |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2367554 |journal=Historical Biology |language=en |pages=1–13 |doi=10.1080/08912963.2024.2367554 |issn=0891-2963}}</ref> known from {{convert|1|cm|in|frac=4|abbr=on}} long fragment and has clear evidence of [[Spiracle (arthropods)|spiracle]]s (breathing holes) attesting to its air-breathing habits.<ref name="Shear.Edgecombe2010" /><ref name="Wilson&Anderson2004">{{cite journal|last=Wilson|first=Heather M.|author2=Anderson, Lyall I.|title=Morphology and taxonomy of Paleozoic millipedes (Diplopoda: Chilognatha: Archipolypoda) from Scotland|journal=Journal of Paleontology |year=2004|volume=78|issue=1 |pages=169–184 |doi=10.1666/0022-3360(2004)078<0169:MATOPM>2.0.CO;2|bibcode=2004JPal...78..169W |s2cid=131201588 }}</ref><ref>{{cite news |title=Fossil millipede found to be oldest land creature |url=http://edition.cnn.com/2004/TECH/science/01/27/environment.britain.fossil.reut/index.html |work=CNN |agency=Reuters |date=Jan 27, 2004 |access-date=December 24, 2021 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304025704/http://edition.cnn.com/2004/TECH/science/01/27/environment.britain.fossil.reut/index.html |url-status=live }}</ref> Other early fossils of millipedes are ''[[Kampecaris|Kampecaris obanensis]]'' and ''[[Archidesmus]]'' sp. from 425 millions years ago in the late [[Silurian]].<ref>{{Cite journal |last1=Brookfield |first1=M. E. |last2=Catlos |first2=E. J. |last3=Suarez |first3=S. E. |date=2021-10-03 |title=Myriapod divergence times differ between molecular clock and fossil evidence: U/Pb zircon ages of the earliest fossil millipede-bearing sediments and their significance |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2020.1762593 |journal=Historical Biology |language=en |volume=33 |issue=10 |pages=2014–2018 |doi=10.1080/08912963.2020.1762593 |bibcode=2021HBio...33.2014B |s2cid=238220137 |issn=0891-2963}}</ref> During the [[Carboniferous]], ''[[Arthropleura]]'' became the largest known land-dwelling invertebrate on record, length exceeding {{convert|2|m|ft|frac=2|abbr=on}}. The reason that ''Arthropleura'' was able to achieve this size is not clearly known; early studies posited that it was a result of high atmospheric oxygen levels, while later studies consider that the lack of competition is more probable.<ref>{{Cite journal |last1=Davies |first1=Neil S. |last2=Garwood |first2=Russell J. |last3=McMahon |first3=William J. |last4=Schneider |first4=Joerg W. |last5=Shillito |first5=Anthony P. |date=2022 |title=The largest arthropod in Earth history: insights from newly discovered Arthropleura remains (Serpukhovian Stainmore Formation, Northumberland, England) |url=https://www.lyellcollection.org/doi/10.1144/jgs2021-115 |journal=Journal of the Geological Society |language=en |volume=179 |issue=3 |doi=10.1144/jgs2021-115 |bibcode=2022JGSoc.179..115D |issn=0016-7649}}</ref> Millipedes also exhibit the earliest evidence of chemical defence, as some [[Devonian]] fossils have defensive gland openings called [[ozopore]]s.<ref name=Shear.Edgecombe2010/>

===Living groups===
[[File:Octoglena sierra (Family Polyzoniidae) (3405605943).jpg|thumb|200px|right|alt=''Octoglena sierra''|''[[Octoglena sierra]]'' ([[Colobognatha]], [[Polyzoniida]])]]
[[File:Anadenobolus monilicornis 03.JPG|thumb|right|200px|alt=''Anadenobolus monilicornis''|''[[Anadenobolus monilicornis]]'' ([[Juliformia]], [[Spirobolida]])]]
[[File:Harpaphe haydeniana 0446.JPG|thumb|right|200px|alt=''Harpaphe haydeniana''|''[[Harpaphe haydeniana]]'' ([[Polydesmida]])]]
The history of scientific millipede classification began with [[Carl Linnaeus]], who in his [[10th edition of Systema Naturae|10th edition of ''Systema Naturae'']], 1758, named seven species of ''[[Julus (millipede)|Julus]]'' as "Insecta Aptera" (wingless insects).<ref name=Linnaeus>{{cite book|author=Caroli Linnaei|year=1758|title=Systema naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis|volume=v.1|pages=639–640|url=https://www.biodiversitylibrary.org/page/727552|publisher=Impensis Direct. Laurentii Salvii|access-date=2018-02-20|archive-date=2018-07-12|archive-url=https://web.archive.org/web/20180712040225/https://www.biodiversitylibrary.org/page/727552|url-status=live}}</ref> In 1802, the French zoologist [[Pierre André Latreille]] proposed the name Chilognatha as the first group of what are now the Diplopoda, and in 1840 the German naturalist [[Johann Friedrich von Brandt]] produced the first detailed classification. The name Diplopoda itself was coined in 1844 by the French zoologist [[Henri Marie Ducrotay de Blainville]]. From 1890 to 1940, millipede taxonomy was driven by relatively few researchers at any given time, with major contributions by [[Carl Attems]], [[Karl Wilhelm Verhoeff]] and [[Ralph Vary Chamberlin]], who each described over 1,000 species, as well as [[Orator F. Cook]], [[Filippo Silvestri]], [[R. I. Pocock]], and [[Henry Wilfred Brolemann|Henry W. Brölemann]].<ref name=SierwaldBond2007/> This was a period when the science of diplopodology flourished: rates of species descriptions were on average the highest in history, sometimes exceeding 300 per year.<ref name="Brewer et al 2012 PLOS">{{cite journal|last1=Brewer|first1=Michael S.|last2=Sierwald|first2=Petra|last3=Bond|first3=Jason E.|title=Millipede taxonomy after 250 years: Classification and taxonomic practices in a mega-diverse yet understudied arthropod group|journal=PLOS ONE |year=2012 |volume=7 |issue=5 |pages=e37240 |doi=10.1371/journal.pone.0037240 |pmid=22615951|pmc=3352885|bibcode=2012PLoSO...737240B|doi-access=free}}</ref>

In 1971, the Dutch biologist [[C. A. W. Jeekel]] published a comprehensive listing of all known millipede genera and families described between 1758 and 1957 in his ''Nomenclator Generum et Familiarum Diplopodorum'', a work credited as launching the "modern era" of millipede taxonomy.<ref name=Shelley2007>{{cite journal|author=Shelley, R. M.|year=2007|title=Taxonomy of extant Diplopoda (Millipeds) in the modern era: Perspectives for future advancements and observations on the global diplopod community (Arthropoda: Diplopoda)|journal=Zootaxa|volume=1668|pages=343–362|url=http://www.mapress.com/zootaxa/2007f/z01668p362f.pdf|doi=10.11646/zootaxa.1668.1.18|access-date=2014-11-11|archive-date=2014-12-26|archive-url=https://web.archive.org/web/20141226050727/http://www.mapress.com/zootaxa/2007f/z01668p362f.pdf|url-status=live}}</ref><ref name=NomenclatorII>{{cite book|last=Shelley|first=Rowland M.|title=Nomenclator generum et familiarum Diplopodorum II : a list of the genus and family-group names in the class Diplopoda from 1958 through 1999|year=2000|publisher=Pensoft|location=Sofia, Bulgaria|isbn=978-954-642-107-4|page=5 |author2=Sierwald, Petra |author3=Kiser, Selena B. |author4= Golovatch, Sergei I.}}</ref> In 1980, the American biologist [[Richard L. Hoffman]] published a classification of millipedes which recognized the Penicillata, Pentazonia, and Helminthomorpha,<ref>{{cite book|last=Hoffman|first= Richard L.|year= 1980|title= Classification of the Diplopoda| publisher=Muséum d'Historie Naturelle|location= Geneva, Switzerland|pages=1–237}}</ref> and the first phylogenetic analysis of millipede orders using modern [[cladistics|cladistic methods]] was published in 1984 by Henrik Enghoff of Denmark.<ref name=Enghoff1984>{{cite journal|last1=Enghoff|first1=H.|title=Phylogeny of millipedes – a cladistic analysis|journal=Journal of Zoological Systematics and Evolutionary Research|date=1984|volume=22|issue=1|pages=8–26|doi=10.1111/j.1439-0469.1984.tb00559.x}}</ref> A 2003 classification by the American myriapodologist Rowland Shelley is similar to the one originally proposed by Verhoeff, and remains the currently accepted classification scheme (shown below), despite more recent molecular studies proposing conflicting relationships.<ref name="SierwaldBond2007" /><ref name=Shear.Edgecombe2010/> A 2011 summary of millipede family diversity by [[William Shear|William A. Shear]] placed the order [[Siphoniulida]] within the larger group Nematophora.<ref name="Shear 2011 class." />

{{clade| style=font-size:90%;line-height:95%;
 |label1='''Diplopoda'''
 |1={{clade
  |label1=Penicillata
  |1={{clade
   |1=[[Polyxenida]]
  }}
  |label2=Chilognatha
  |2={{clade
   |label1=[[Pentazonia]]
   |1={{clade
    |label1=Limacomorpha
    |1=[[Glomeridesmida]]
    |label2=[[Oniscomorpha]]
    |2={{clade
     |1=[[Glomerida]]
     |2=[[Sphaerotheriida]]
    }}
   }}
   |label2=[[Helminthomorpha]]
   |2={{clade
    |label1=[[Colobognatha]]
    |1={{clade
     |1=[[Platydesmida]]
     |2=[[Siphonocryptida]]
     |3=[[Polyzoniida]]
     |4=[[Siphonophorida]]
    }}
    |label2=[[Eugnatha]]
    |2={{clade
     |label1=[[Nematophora]]
     |1={{clade
      |1=[[Chordeumatida]]
      |2=[[Callipodida]]
      |3=[[Stemmiulida]]
      |4=[[Siphoniulida]]
     }}
     |label2=[[Merocheta]]
     |2={{clade
      |1=[[Polydesmida]]
     }}
     |label3=[[Juliformia]]
     |3={{clade
      |1=[[Julida]]
      |2=[[Spirobolida]]
      |3=[[Spirostreptida]]
     }}
    }}
   }}
  }}
 }}
}}

===Fossil record===
In addition to the 16 living orders, there are 9 extinct orders and one superfamily known only from fossils. The relationship of these to living groups and to each other is controversial. The extinct Arthropleuridea was long considered a distinct myriapod class, although work in the early 21st century established the group as a subclass of millipedes.<ref name=Wilson&Shear2000>{{cite journal|last=Wilson|first=Heather M.|author2=Shear, William A.|title=Microdecemplicida, a new order of minute arthropleurideans (Arthropoda: Myriapoda) from the Devonian of New York State, U.S.A|journal=Transactions of the Royal Society of Edinburgh: Earth Sciences|year=2000|volume=90|issue=4|pages=351–375|doi=10.1017/S0263593300002674|s2cid=129597005 }}</ref><ref name=Kraus&Brauckmann2003/><ref name=Kraus2005>{{cite journal|last=Kraus|first= O.|year= 2005|title= On the structure and biology of ''Arthropleura'' species (Atelocerata, Diplopoda; Upper Carboniferous/Lower Permian)|journal= Verhandlungen des Naturwissenschaftlichen Vereins in Hamburg|volume= 41|pages= 5–23}}</ref> Several living orders also appear in the fossil record. Below are two proposed arrangements of fossil millipede groups.<ref name="SierwaldBond2007" /><ref name=Shear.Edgecombe2010/> Extinct groups are indicated with a [[dagger (typography)|dagger]] (†). The extinct order [[Zosterogrammida]], a chilognath of uncertain position,<ref name=Shear.Edgecombe2010/> is not shown.

{{cladogram|title=
|caption=Alternate hypothesis of fossil relationships<ref name=SierwaldBond2007/><ref name=Kraus&Brauckmann2003>{{cite journal|last1=Kraus|first1= O.|first2=C.|last2 =Brauckmann |title=Fossil giants and surviving dwarfs. Arthropleurida and Pselaphognatha (Atelocerata, Diplopoda): characters, phylogenetic relationships and construction|journal= Verhandlungen des Naturwissenschaftlichen Vereins in Hamburg|volume= 40 |year=2003|pages= 5–50}}</ref>
|clades={{clade|style=font-size:90%;line-height:95%;
|1={{clade
 |label1=Penicillata
 |1={{clade
  |label1=†[[Arthropleuridea]]
  |1={{clade
   |1=†[[Arthropleurida]]
   |2=†[[Eoarthropleurida]]
  }}
  |2=[[Polyxenida]]
 }}
 |label2=
 |2={{clade
  |1=†[[Microdecemplicida]]
  |2=[[Chilognatha]]
 }}
}}
}}
}}
{{clade| style=font-size:90%;line-height:95%;
 |label1='''Diplopoda'''
 |1={{clade
  |label1=Penicillata
  |1=[[Polyxenida]]
  |label2=Chilognatha
  |2={{clade
   |label1=†[[Arthropleuridea]]
   |1={{clade
    |1=†[[Arthropleurida]]
    |2=†[[Eoarthropleurida]]
    |3=†[[Microdecemplicida]]
   }}
   |label2=
   |2={{clade
    |label1=[[Pentazonia]]
    |1=†[[Amynilyspedida]]
    |label2=Helminthomorpha
    |2={{clade
     |label1=†[[Archipolypoda]]
     |1={{clade
      |1=†[[Archidesmida]]
      |2=†[[Cowiedesmida]]
      |3=†[[Euphoberiida]]
      |4=†[[Palaeosomatida]]
     }}
     |label2=
     |2={{clade
      |1=†[[Pleurojulida]]
      |2=[[Colobognatha]]
      |label3=Eugnatha
      |3={{clade
       |label1=
       |1={{clade
        |1=Nematophora
        |2=[[Polydesmida]]
       }}
       |label2=[[Juliformia]]
       |2={{clade
        |1=[[Julida]]
        |2=[[Spirobolida]]
        |3=[[Spirostreptida]]
        |4=†[[Xyloiuloidea]]|state4=dashed
       }}
      }}
     }}
    }}
   }}
  }}
 }}
}}

===Relation to other myriapods===
[[File:Pauropus huxleyi.jpg|thumb|alt=Pauropod|Pauropods are thought to be the closest relative of millipedes.]]
Although the relationships of millipede orders are still the subject of debate, the class Diplopoda as a whole is considered a [[monophyletic group]] of arthropods: all millipedes are more closely related to each other than to any other arthropods. Diplopoda is a class within the arthropod subphylum [[Myriapoda]], the myriapods, which includes [[centipede]]s (class Chilopoda) as well as the lesser-known [[Pauropoda|pauropods]] (class Pauropoda) and [[symphyla]]ns (class Symphyla). Within myriapods, the closest relatives or [[sister group]] of millipedes has long been considered the pauropods, which also have a collum and diplosegments.<ref name=SierwaldBond2007 />

===Distinction from centipedes===
The differences between millipedes and centipedes are a common question from the general public.<ref name="Shelley 1999">{{cite journal |last=Shelley |first=Rowland M. |title=Centipedes and millipedes with emphasis on North American fauna |journal=The Kansas School Naturalist |year=1999 |volume=45 |issue=3 |pages=1–16 |url=http://www.emporia.edu/ksn/v45n3-march1999/ |access-date=2013-10-14 |archive-url=https://web.archive.org/web/20161112025334/http://www.emporia.edu/ksn/v45n3-march1999/ |archive-date=2016-11-12 |url-status=dead }}</ref> Both groups of myriapods share similarities, such as long, multi-segmented bodies, many legs, a single pair of antennae, and the presence of [[Tömösváry organ|postantennal organ]]s, but have many differences and distinct evolutionary histories, as the [[most recent common ancestor]] of centipedes and millipedes lived around 450 to 475 million years ago in the Silurian.<ref name=Brewer&Bond2013>{{cite journal|last1=Brewer|first1=Michael S.|last2=Bond|first2=Jason E.|title=Ordinal-level phylogenomics of the arthropod class Diplopoda (Millipedes) based on an analysis of 221 nuclear protein-coding loci generated using next-generation sequence analyses|journal=PLOS ONE |year=2013|volume=8|issue=11|pages=e79935|doi=10.1371/journal.pone.0079935|pmid=24236165|pmc=3827447|bibcode=2013PLoSO...879935B|doi-access=free}}</ref> The head alone exemplifies the differences; millipedes have short, geniculate (elbowed) [[Antenna (biology)|antenna]]e for probing the substrate, a pair of robust mandibles and a single pair of maxillae fused into a lip; centipedes have long, threadlike antennae, a pair of small mandibles, two pairs of maxillae and a pair of large poison claws.<ref name=Blower>{{cite book|author=Blower, John Gordon|title=Millipedes: Keys and Notes for the Identification of the Species|url=https://books.google.com/books?id=VQsVAAAAIAAJ&pg=PA1 |year=1985 |publisher=Brill Archive |isbn=978-90-04-07698-3 |page=1}}</ref>
[[File:Millipede centipede side-by-side.png|thumb|alt=Millipede and centipede|A representative millipede and centipede (not necessarily to scale)]]
{| class="wikitable"
|+ '''Millipede and centipede differences'''<ref name="Shelley 1999"/>
! scope="col" style="width:100pt;"| Trait
! scope="col" style="width:260pt;"| Millipedes
! scope="col" style="width:270pt;"| Centipedes
|- valign="top"
! scope="row" | Legs
| Two pairs on most body segments; attached to underside of body
| One pair per body segment; attached to sides of body; last pair extends backwards
|- valign="top"
! scope="row" | Locomotion
| Generally adapted for burrowing or inhabiting small crevices; slow-moving
| Generally adapted for running, except for the burrowing [[Geophilomorpha|soil centipedes]]
|- valign="top"
! scope="row" | Feeding
| Primarily detritivores, some herbivores, few carnivores; no venom
| Primarily carnivores with front legs modified into venomous fangs
|- valign="top"
! scope="row" | Spiracles
| On underside of body
| On the sides or top of body
|- valign="top"
! scope="row" | Reproductive openings
| Third body segment
| Last body segment	
|- valign="top"
! scope="row" | Reproductive behaviour
| Male generally inserts spermatophore into female with gonopods
| Male produces spermatophore that is usually picked up by female
|}