''Limulus'' is a genus of

horseshoe crab Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scor ...

, with one extant species, the

Atlantic horseshoe crab The Atlantic horseshoe crab (''Limulus polyphemus''), also known as the American horseshoe crab, is a species of horseshoe crab, a kind of marine biology, marine and Brackish water, brackish chelicerate arthropod. It is found in the Gulf of Mexic ...

(''Limulus polyphemus''). One fossil species is currently assigned to the genus though several other species have been named, which have since been assigned to other genera. Currently valid species include: *''

Limulus polyphemus The Atlantic horseshoe crab (''Limulus polyphemus''), also known as the American horseshoe crab, is a species of horseshoe crab, a kind of marine and brackish chelicerate arthropod. It is found in the Gulf of Mexico and along the Atlantic coast ...

'' (

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of ''Systema Naturae'', the starting point of modern zoologic ...

) *'' Limulus coffini''

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ...

Reeside & Harris, 1952-

Pierre Shale The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada to New Mexico. The Pierre Shale was described by Fielding Bradford Meek, Meek a ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, Late Cretaceous (

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

) Doubtful species include:Dunlop, J. A., Penney, D. & Jekel, D. 2013. A summary list of fossil spiders and their relatives. In Platnick, N. I. (ed.) ''The world spider catalog, version 14.0'' American Museum of Natural History, online at http://research.amnh.org/entomology/spiders/catalog/index.html * '' Limulus nathorsti''

Jackson, 1906-

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

Tentative species: *''" Limulus" decheni''

Zinken, 1862-

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

(considered by some intermediate between ''Limulus'' and ''

Tachypleus ''Tachypleus'' is a genus of south, southeast and east Asian horseshoe crabs in the family Limulidae. Species There are two extant (living) species: * '' Tachypleus gigas'' (Müller, 1785) * '' Tachypleus tridentatus'' ( Leach, 1819) And two ...

'')

References

Xiphosura Prehistoric chelicerates Extant Triassic first appearances {{paleo-arthropod-stub