The Echinoid Directory

• Test subpentagonal in outline; margin extremely thin and sharp.
• Apical disc central with 4 gonopores; hydropores scattered over surface.
• Petals relatively short (a little less than 50% radial distance); bowed and closed distally.
• Five slit-like ambulacral lunules and a slit-like anal lunule in the type species. Anterior lunule absent in some species.
• Interambulacral zones similar in width to ambulacra at ambitus. Pores and tube-feet extending across interambulacral zones.
• Posterior interambulacrum continuous on oral surface, others disjunct and separated by two pairs of ambulacral plates.
• Periproct oral, close to peristome; opening in first paired interambulacral plates and bounded adorally by basicoronal plate but not indenting it.
• Food grooves present, bifurcating after first ambulacral plates; highly branched distally.
• Internal radial partitions highly developed as irregular meshwork (microcannal system present).

Pliocene to Recent, East coast of America.

Leodia richardsoni Gray, 1851 (= Echinodiscus sexiesperforatus Leske, 1778, p. 199), by original designation.

• Leodia sexiesperforata (Leske, 1778); Pleistocene to Recent, East coast of America from Buenos Aries to North Carolina, including the Caribbean and Bermuda.
• L. divinata Mooi & Peterson 2000; Mare Formation, ?Lower Pliocene, Venezuela.

Clypeasteroida; Scutellina; Scutelliformes; Scutellidea; Mellitidae.

Monophyletic.

This genus has been reviewed and described in detail by Mooi & Peterson (2000). It differs from Mellita in having shorter petals, and with the periproct positioned at the triple junction of the basicoronal interambulacral plate and the succeeding paired interambulacral plates, and in having two pairs of ambulacral plates separating the basicoronal and post-basicoronal plates in lateral and anterior paired interambulacral zones. The presence of a fifth lunule in ambulacrum III is not diagnostic, since some Mellita species also show this character (see Mooi & Peterson 2000 for discussion).

Gray, J. E. 1851. Proceedings of the Zoological Society 19, p. 36.

Mooi, R. & Peterson, D. 2000. A new species of Leodia (Clypeasteroida: Echinoida) from the Neogene of Venezuela and its importance in the phylogeny of mellitid sand dollars. Journal of Paleontology 74, 1083-1092.