The Echinoid Directory

• Test ovate with deep anterior sulcus; test depressed in profile with moderately sharp ambitus.
• Apical disc ethmolytic with four gonopores; central.
• Anterior ambulacrum only weakly sunken adapically but deepening towards ambitus; pore-pairs small and undifferentiated; no funnel-building tube-feet.
• Paired ambulacra petaloid and flush; anterior pair slightly longer than posterior. Petals bowed and closed distally; relatively short.
• Peristome close to anterior border and facing forward into frontal groove. Labrum projecting to cover peristome in oral view.
• Labral plate short and wide; extending half-way down the first ambulacral plate only. Sternal plates long and parallel edged. Episternals paired. Sternal-episternal suture straight.
• Periproct on posterior truncate face.
• Subanal fasciole present; shield-shaped.
• Peripetalous fasciole present; not indented behind anterior petals. Normally doubled or forming an irregular network.
• Aboral tuberculation heterogeneous; primary tubercles developed within peripetalous fasciole and along posterior interambulacral ridge.

Recent; Caribbean.

Macropneustes spatangoides Agassiz, 1883, p. 64, by original designation.

• P. spatangoides Agassiz, 1883; Recent; Antilles.
• P. angularis Chesher, 1968; Recent, Caribbean.

Spatangoida, Micrasterina, Spatangidae.

Presumed monophyletic.

Close to Spatangus but differing from that taxon in having an irregular peripetalous fasicole and a deeper frontal groove.

Chesher (1968) gives a very full account of both species.

Chesher, R. H. 1968. The systematics of sympatric species in West Indian spatangoids: A revision of the genera Brissopsis, Plethotaenia, Paleopneustes, and Saviniaster. Studies in Tropical Oceanography 7, 1-168, pls 1-35.

Clark, H. L. 1917. Memoirs of the Museum of Comparative Zoology, Harvard 46 (2).