''Eucidaris'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of cidaroid

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

s known as slate pencil urchins (named after slate pencil). They are characterised by a moderately thick

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film) ...

, a usually monocyclic apical disc, perforate and non-crenulate tubercles and nearly straight ambulacra with horizontal pore pairs. The primary spines are few and widely spaced, stout with blunt flat tips and beaded ornamentation and the secondary spines are short and apressed. They originated in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

and

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

members of the genus are found in the tropical

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

Ocean, East Pacific, Atlantic Ocean and

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

Species

The World Register of Marine Species lists the following species: * '' Eucidaris australiae'' Mortensen, 1950 * † '' Eucidaris coralloides'' Fell, 1954 * '' Eucidaris galapagensis'' Döderlein, 1887 * '' Eucidaris metularia'' (

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...

, 1816) * † '' Eucidaris strobilata'' Fell, 1954 * '' Eucidaris thouarsii'' (

Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he recei ...

& Desor, 1846) * '' Eucidaris tribuloides'' (

, 1816) ;Species brought into synonymy: * ''Eucidaris clavata'' Mortensen, 1928: synonym of ''Eucidaris tribuloides'' (Lamarck, 1816) Eucidaris metularia.jpg, '' Eucidaris metularia'' Eucidaris Baltimore Aquarium.jpg, '' Eucidaris tribuloides'' Cidaroid urchin in Galapagos.jpg, '' Eucidaris galapagensis''

References

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivantes et fossiles. Thèses présentées à la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles 503, Adolphe Jourdan, Alger, 131 pp
{{Taxonbar, from=Q3458737 Cidaridae Cidaroida genera