The Echinoid Directory

• Test ovate without anterior sulcus; depressed in profile with slightly keeled sternum.
• Apical disc ethmophract; no gonopores open; anterior of centre.
• Anterior ambulacrum narrow and flush, with plates slightly wider than tall; pores rudimentary.
• Paired ambulacra subpetaloid, flush. Pore-pairs closely spaced with little perradial gap between columns. The posterior petaloid regions longer than the lateral petaloid regions.
• Peristome large and D-shaped; facing downwards.
• Labral plate long and wedge-like, extending to amb. 3 which is enlarged. Sternal plates short and triangular; fully tuberculate. Episternal plates paired and symmetric; indented by amb 6 to rear. Post episternal plates paired and symmetric.
• Periproct on posterior truncate face; framed on oral side by Iamb 5a/b.
• Narrow peripetalous fasciole present; not indented laterally but displaced posteriorly in posterior Iamb. Subanal fasciole present, with 3 amb pore-pairs.
• Scattered heterogeneous tuberculation inside peripetalous fasciole.

Recent, Hawaii.

Pycnolampas oviformis Agassiz & Clark, 1907. p. 253; by original designation.

• Only the type species.

Spatangoida, Micrasterina, Maretiidae (or Macropneustidae).

Monotypic.

Based on juveniles, since none of the specimens show open genital pores (Clark, 1917, p. 154). Possibly just a juvenile species of Linopneustes.

Agassiz, A. & Clark, H. L. 1907. Preliminary reports on the Echini collected in 1902, among the Hawaiian Islands, by the U. S. Fish Commission steamer “Albatross”, in charge of Commander Chauncey Thomas, U. S. N. commanding. Bulletin of the Museum of Comparative Zoology, Harvard College, 50, 231-259.