# List of xiphosuran genera

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 | |
| †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 | China | |
* 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 |