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^[1] 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[2] 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.[2] †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 †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[3] Jr. synonym N/A N/A Synonym of Limulus. †Xiphosuroides[4] Shpinev & Vasilenko 2018 Valid Carboniferous  Russia †Yunnanolimulus Zhang, Hu, Zhou, Iv & Bai 2009 Valid Triassic  China		Austrolimulus fletcheri Belinurus lunatus Carcinoscorpius rotundicauda Euproops danae Limulus polyphemus Mesolimulus walchi Prestwichia anthrax Tachypleus tridentatus

Xiphosuran ichnogenera