This list of xiphosurans is a comprehensive listing of all genera that have ever been included in the order Xiphosura, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomen dubium), or were not formally published (nomen nudum), as well as junior synonyms of more established names, genera that are no longer considered xiphosurans and misspellings. The list currently includes 54 names out of which 31 are considered valid xiphosuran genera.

As of 2019 there were around 80 extinct species of xiphosurans and 4 extant species of xiphosurans recognized as valid.

Naming conventions and terminology

There is no "official" or "canonical" list of xiphosuran genera. The closest thing is found contained in the regularly updated Summary list of fossil spiders and their relatives in the World Spider Catalog, which include just the extinct species. The vast majority or all of the content of the list below, including the valid genera, preoccupied names, junior synonyms, misspellings, taxonomical classifications and sites of discovery, is based upon the 2019 edition of the summary list.

Naming conventions and terminology follow the International Code of Zoological Nomenclature. Technical terms used include:

  • Junior synonym: A name which describes the same taxon as a previously published name. If two or more genera are formally designated and the type specimens are later assigned to the same genus, the first to be published (in chronological order) is the senior synonym, and all other instances are junior synonyms. Senior synonyms are generally used, except by special decision of the ICZN, but junior synonyms cannot be used again, even if deprecated. Junior synonymy is often subjective, unless the genera described were both based on the same type specimen.
  • Nomen nudum (Latin for "naked name"): A name that has appeared in print but has not yet been formally published by the standards of the ICZN. Nomina nuda (the plural form) are invalid, and are therefore not italicized as a proper generic name would be. If the name is later formally published, that name is no longer a nomen nudum and will be italicized on this list. Often, the formally published name will differ from any nomina nuda that describe the same specimen.
  • Nomen oblitum (Latin for "forgotten name"): A name that has not been used in the scientific community for more than fifty years after its original proposal.
  • Preoccupied name: A name that is formally published, but which has already been used for another taxon. This second use is invalid (as are all subsequent uses) and the name must be replaced. As preoccupied names are not valid generic names, they will also go unitalicized on this list.
  • Nomen dubium (Latin for "dubious name"): A name describing a fossil with no unique diagnostic features.

Xiphosuran genera

† = Extinct

Genus Author(s) Year Status Age Location Notes †Alanops Racheboeuf 2002 Valid Carboniferous France †Anacontium Raymond 1944 Valid Permian United States †Archeolimulus Chlupáč 1963 Valid Middle Ordovician Czech Republic †Austrolimulus Riek 1955 Valid Triassic Australia †Belinuropsis Matthew 1910 Nomen dubium Carboniferous Canada Too poorly preserved to be assigned to any particular arthropod group. †Belinurus Bronn 1839 Valid Carboniferous Canada England United States Ukraine Wales †Bellinuroopsis Chernyshev 1933 Valid Devonian Russia †Bellinurus Pictet 1846 Synonym N/A N/A Invalid name, Belinurus (Bronn, 1839) has priority. †Bifarius Tasch 1961 Misidentification N/A N/A Misidentified, an insect. Carcinoscorpius Pocock 1902 Valid ??? – present India Indonesia Malaysia Philippines Singapore Thailand †Casterolimulus Holland, Erickson & O’Brien 1975 Valid Cretaceous United States †Ciurcalimulus Lamsdell 2025 Valid Silurian United States †Crenatolimulus Feldmann, Schweitzer, Dattilo & Farlow 2011 Valid Cretaceous United States †Dubbolimulus Pickett 1984 Jr. synonym N/A N/A Synonym of Paleolimulus. †Elleria Raymond 1944 Valid Devonian United States †Elmocephalus Tasch 1963 Misidentification N/A N/A Misidentified, a crustacean? †Eolimulus Moberg 1892 Nomen dubium Cambrian Sweden †Euproops Meek 1867 Valid Carboniferous - Permian? England France Germany South Korea United States Wales †Heterolimulus Via Boada & Villalta 1966 Jr. synonym N/A N/A Synonym of Tachypleus. †Hypatocephala Tasch 1961 Misidentification N/A N/A Misidentified, an insect. †Kasibelinurus Pickett 1993 Valid Devonian Australia China †Koenigiella Raymond 1944 Jr. synonym N/A N/A Synonym of Bellinurus. †Lemoneites Flower 1969 Misidentification N/A N/A Misidentified, an echinoderm. †Limulitella Størmer 1952 Valid Triassic – Jurassic France Germany Madagascar Netherlands Russia Tunisia †Limulites Schimper 1853 Preoccupied N/A N/A Preoccupied name, changed to Limulitella. Limulus Müller 1785 Valid Triassic – present England Germany Mexico Poland United States †Liomesaspis Raymond 1944 Valid Carboniferous - Permian Germany United Kingdom United States †Lophodesmus Tesakov & Alekseev 1992 Preoccupied N/A N/A Preoccupied name, changed to Maldybulakia. †Lunataspis Young & Nowlan 2008 Valid Ordovician Canada †Maldybulakia Tesakov & Alekseev 1998 Valid Silurian Australia Kazakhstan †Mesolimulus Størmer 1952 Valid Triassic – Cretaceous England Germany Russia Spain †Neobelinuropsis Eller 1938 Jr. synonym N/A N/A Synonym of Bellinuroopsis. †Palatinaspis Malz & Poschmann 1993 Jr. synonym N/A N/A Synonym of Liomesaspis. †Paleolimulus Dunbar 1923 Valid Carboniferous - Triassic Australia Germany Russia United States Ukraine †Panduralimulus Allen & Feldman 2005 Valid Permian United States †Permolimulinella Tasch 1963 Misidentification N/A N/A Misidentified, an insect. †Pincombella Chapman 1932 Misidentification N/A N/A Misidentified, an insect. †Prestwichia Woodward 1867 Preoccupied N/A N/A Preoccupied name, changed to Euproops. †Prestwichianella Cockerell 1905 Replacement name N/A N/A Replacement name for Prestwichia. †Pringlia Raymond 1944 Jr. synonym N/A N/A Synonym of Liomesaspis. †Prolimulus Frič 1899 Valid Carboniferous Czech Republic †Psammolimulus Lange 1923 Valid Triassic Germany †Rolfeia Waterston 1985 Valid Carboniferous Scotland †Steropsis Baily 1869 Jr. synonym N/A N/A Synonym of Bellinurus. †Strongylocephalus Tasch 1961 Misidentification N/A N/A Misidentified, an insect. Tachypleus Leach 1819 Valid Triassic – present China Indonesia Japan Lebanon Malaysia Philippines South Korea Spain Taiwan Vietnam †Tarracolimulus Romero & Via Boada 1977 Valid Triassic Spain †Vaderlimulus Lerner, Lucas & Lockley 2017 Valid Triassic United States †Valloisella Racheboeuf 1992 Valid Carboniferous France †"Veltheimia" Beyschlag & von Fritsch 1899 Nomen nudum Carboniferous? Germany †Victalimulus Riek & Gill 1971 Valid Cretaceous Australia †Willwerathia Størmer 1969 Valid Devonian Germany †Xaniopyramis Siveter & Selden 1987 Valid Carboniferous England Xiphosura Jr. synonym N/A N/A Synonym of Limulus. †Xiphosuroides Shpinev & Vasilenko 2018 Valid Carboniferous Russia †Yunnanolimulus Zhang, Hu, Zhou, Iv & Bai 2009 Valid Triassic ChinaAustrolimulus fletcheri Belinurus lunatus Carcinoscorpius rotundicauda Euproops danae Limulus polyphemus Mesolimulus walchi Prestwichia anthrax Tachypleus tridentatus
GenusAuthor(s)YearStatusAgeLocationNotes
†AlanopsRacheboeuf2002ValidCarboniferousFrance
†AnacontiumRaymond1944ValidPermianUnited States
†ArcheolimulusChlupáč1963ValidMiddle OrdovicianCzech Republic
†AustrolimulusRiek1955ValidTriassicAustralia
†BelinuropsisMatthew1910Nomen dubiumCarboniferousCanadaToo poorly preserved to be assigned to any particular arthropod group.
†BelinurusBronn1839ValidCarboniferousCanada England United States Ukraine Wales
†BellinuroopsisChernyshev1933ValidDevonianRussia
†BellinurusPictet1846SynonymN/AN/AInvalid name, Belinurus (Bronn, 1839) has priority.
†BifariusTasch1961MisidentificationN/AN/AMisidentified, an insect.
CarcinoscorpiusPocock1902Valid??? – presentIndia Indonesia Malaysia Philippines Singapore Thailand
†CasterolimulusHolland, Erickson & O’Brien1975ValidCretaceousUnited States
†CiurcalimulusLamsdell2025ValidSilurianUnited States
†CrenatolimulusFeldmann, Schweitzer, Dattilo & Farlow2011ValidCretaceousUnited States
†DubbolimulusPickett1984Jr. synonymN/AN/ASynonym of Paleolimulus.
†ElleriaRaymond1944ValidDevonianUnited States
†ElmocephalusTasch1963MisidentificationN/AN/AMisidentified, a crustacean?
†EolimulusMoberg1892Nomen dubiumCambrianSweden
†EuproopsMeek1867ValidCarboniferous - Permian?England France Germany South Korea United States Wales
†HeterolimulusVia Boada & Villalta1966Jr. synonymN/AN/ASynonym of Tachypleus.
†HypatocephalaTasch1961MisidentificationN/AN/AMisidentified, an insect.
†KasibelinurusPickett1993ValidDevonianAustralia China
†KoenigiellaRaymond1944Jr. synonymN/AN/ASynonym of Bellinurus.
†LemoneitesFlower1969MisidentificationN/AN/AMisidentified, an echinoderm.
†LimulitellaStørmer1952ValidTriassic – JurassicFrance Germany Madagascar Netherlands Russia Tunisia
†LimulitesSchimper1853PreoccupiedN/AN/APreoccupied name, changed to Limulitella.
LimulusMüller1785ValidTriassic – presentEngland Germany Mexico Poland United States
†LiomesaspisRaymond1944ValidCarboniferous - PermianGermany United Kingdom United States
†LophodesmusTesakov & Alekseev1992PreoccupiedN/AN/APreoccupied name, changed to Maldybulakia.
†LunataspisYoung & Nowlan2008ValidOrdovicianCanada
†MaldybulakiaTesakov & Alekseev1998ValidSilurianAustralia Kazakhstan
†MesolimulusStørmer1952ValidTriassic – CretaceousEngland Germany Russia Spain
†NeobelinuropsisEller1938Jr. synonymN/AN/ASynonym of Bellinuroopsis.
†PalatinaspisMalz & Poschmann1993Jr. synonymN/AN/ASynonym of Liomesaspis.
†PaleolimulusDunbar1923ValidCarboniferous - TriassicAustralia Germany Russia United States Ukraine
†PanduralimulusAllen & Feldman2005ValidPermianUnited States
†PermolimulinellaTasch1963MisidentificationN/AN/AMisidentified, an insect.
†PincombellaChapman1932MisidentificationN/AN/AMisidentified, an insect.
†PrestwichiaWoodward1867PreoccupiedN/AN/APreoccupied name, changed to Euproops.
†PrestwichianellaCockerell1905Replacement nameN/AN/AReplacement name for Prestwichia.
†PringliaRaymond1944Jr. synonymN/AN/ASynonym of Liomesaspis.
†ProlimulusFrič1899ValidCarboniferousCzech Republic
†PsammolimulusLange1923ValidTriassicGermany
†RolfeiaWaterston1985ValidCarboniferousScotland
†SteropsisBaily1869Jr. synonymN/AN/ASynonym of Bellinurus.
†StrongylocephalusTasch1961MisidentificationN/AN/AMisidentified, an insect.
TachypleusLeach1819ValidTriassic – presentChina Indonesia Japan Lebanon Malaysia Philippines South Korea Spain Taiwan Vietnam
†TarracolimulusRomero & Via Boada1977ValidTriassicSpain
†VaderlimulusLerner, Lucas & Lockley2017ValidTriassicUnited States
†ValloisellaRacheboeuf1992ValidCarboniferousFrance
†"Veltheimia"Beyschlag & von Fritsch1899Nomen nudumCarboniferous?Germany
†VictalimulusRiek & Gill1971ValidCretaceousAustralia
†WillwerathiaStørmer1969ValidDevonianGermany
†XaniopyramisSiveter & Selden1987ValidCarboniferousEngland
XiphosuraJr. synonymN/AN/ASynonym of Limulus.
†XiphosuroidesShpinev & Vasilenko2018ValidCarboniferousRussia
†YunnanolimulusZhang, Hu, Zhou, Iv & Bai2009ValidTriassicChina
Austrolimulus fletcheri
Belinurus lunatus
Carcinoscorpius rotundicauda
Euproops danae
Limulus polyphemus
Mesolimulus walchi
Prestwichia anthrax
Tachypleus tridentatus

Xiphosuran ichnogenera

Genus Author(s) Year Status Age Location †Kouphichnium Nopcsa 1923 Valid Carboniferous - Jurassic Argentina England France Germany Mexico Poland United States †Selenichnites Romano & Whyte 1987 Valid Cambrian – Jurrasic N/A
GenusAuthor(s)YearStatusAgeLocation
†KouphichniumNopcsa1923ValidCarboniferous - JurassicArgentina England France Germany Mexico Poland United States
†SelenichnitesRomano & Whyte1987ValidCambrian – JurrasicN/A

See also