The Echinoid Directory

• Test ovate without anterior sulcus; posterior face short and truncate. Test flattened in profile with flat base.
• Apical disc ethmolytic, with 4 gonopores. Madreporic plate projecting beyond the posterior ocular plates. Anterior of centre.
• Anterior ambulacrum narrow and flush; pore-pairs small, simple isopores.
• Other ambulacra petaloid and flush. Lateral petals flexed anteriorly and extending to ambitus; almost at 180 degrees. Posterior petals also extending to ambitus and only weakly diverging. Pore-pairs conjugate; no occluded plates distally.
• Periproct large; on short, steeply inclined truncate face; bound on oral side by paired Iamb plates 4a/b.
• Peristome large and kidney-shaped; rather distant from the anterior border.
• Phyllodes extremely well developed in lateral ambulacra.
• Plastron plating: labral plate very long and wedge-like; extending to 4th ambulacral plate; may be disjunct in some species. Sternal plates short and triangular; tubercle-free. Episternal plates symmetrically paired; strongly indented to rear by ambulacral plates 6-8.
• Scattered primary tubercles in interambulacral zones over aboral surface, especially anteriorly. Areoles weakly indented but not sunken.
• On oral surface lateral interambulacra with large, aligned tubercles with sunken areoles.
• Plastron short and triangular; primary tubercles confined to very posterior section (sternal plates almost naked).
• No fascioles as adult.

Recent, Indo-Pacific.

Eurypatagus ovalis Mortensen, 1948, p. 133, by original designation.

Spatangoida, Micrasterina, unnamed taxon 2.

Uncertain.

Differs from Maretia in having distally open petals which are narrow with narrow perradial zones. Resembles Platybrissus but can be distinguished in having a different shaped peristome, longer petals and better developed phyllodes.

Mortensen, T. 1950. A monograph of the Echinoidea. V. Spatangoida 1. C. A. Reitzel, Copenhagen.