The Echinoid Directory

• Test ovate with faint anterior sulcus; base flat and depressed in profile with short truncate posterior face. Thin-plated.
• Apical disc ethmolytic with four gonopores; anterior of centre.
• Anterior ambulacrum flush and narrow aborally, with small steeply oblique pore-pairs.
• Paired ambulacra petaloid; petals long, parallel-sided with wide interporal zone and open distally without occluded plates. Petals extend to ambitus. Pore-pairs conjugate.
• Peristome D-shaped and slightly depressed but downward-facing.
• Labral plate longitudinally elongate; wedge-shaped; extending to third or fourth ambulacral plate. Sternal plates paired, short and triangular; fully tuberculate. Episternal plates paired and strongly tapered posteriorly (indented by ambulacral plate 6).
• Periproct on posterior truncate face; slightly wider than tall.
• Subanal fasciole present enclosing three subanal tube-feet.
• Thin peripetalous fasciole present, not indented interradially.
• Scattered primary tubercles over the aboral surface in all interambulacral zones.

Recent, Indian Ocean.

Eurypneustes denudatus Koehler, 1914, p. 71, by original designation.

• E. denudatus (Koehler, 1914); Recent, Ceylon.
• E. rubens (Koehler, 1914); Recent, Ceylon.

Spatangoida, Micrasterina, unnamed taxon 2.

Probably monophyletic.

Closely related to Linopneustes and Eurypatagus, sharing with those taxa its long open petals and distinctive plastron structure. It differs from Linopneustes in lacking a frontal groove and in having somewhat more strongly conjugate pore-pairs. It is distinguished from Eurypatagus by the presence of a peripetalous fasciole.

Name proposed as a replacement for Eurypneustes Koehler, non Duncan & Sladen, 1882.

Koehler, R. 1914. Change of name in an Indian genus of Echinoidea. Records of the Indian Museum 10, p. 213.

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