The Echinoid Directory

• Apical disc hemicyclic with ocular V commonly exsert.
• Test oval in outline, with long axis passing through ocular I and genital plate 3; peristome and disc likewise ovate.
• Ambulacral plating polygeminate with 5-7 pore-pairs to a compound plate, arranged in arcs in the type species; arcs separated by adradial secondary tubercles.
• One large primary tubercle to each ambulacral and interambulacral plate.
• Buccal notches small; phyllodes not developed.
• Spines stout and pointed; usually a little less than the test diameter at their longest.

Early Miocene to Recent; France, North Africa and the Mediterranean, tropical Atlantic and Indo-Pacific.

Echinus lucunter Linnaeus, 1758, p. 665, by original designation.

• E. lucunter (Linneus, 1758); Recent, Caribbean and both sides of the Atlantic, 0-45 m.
• E. viridis Agassiz, 1863; Recent, West Indies.
• E. vanbrunti Agassiz, 1863; Recent, Western coast of America (California to Peru).
• E. mathaei (Blainville, 1825); Early Miocene to Recent, Mediterranean to Indo-West Pacific.
• E. insularis Clark, 1912; Recent, Easter, Galapagos and Socorro Islands.

Camarodonta; Echinoida; Echinometridae.

Probably monophyletic

The characteristic ovate shape and oblique axis distinguish Echinometra from most other echinid genera. Parasalenia also has an ovate test, but its long axis passes through ocular plate III and genital plate 5. Colobocentrotus, Podophora and Heterocentrotus all have similarly ovate tests, but they are distinguished by having short peg-like aboral secondary spines as opposed to the long, pointed spines of Echinometra, and more massive and typically flattened or facetted primary spines. 'Echinometra' prisca Cotteau has trigeminate ambulacra and an unknown axis of elongation, and is here retained in its own genus, Plagiechinus.

Echinometra thomsoni d'Archiac & Haime, 1853, from the Eocene of Sind, Pakistan, is an indeterminate regular euechinoid.