The Echinoid Directory

• Test highly elongate and laterally compressed; no frontal groove.
• Apical disc ethmolytic, with 2 or 4 gonopores (in the type species the anterior two gonopores are wanting and genital plates are fused).
• Anterior ambulacrum very weakly depressed adapically, but flush by ambitus; with single series of enlarged pore-pairs bearing tube-feet that end in a large rosetted disc.
• Paired ambulacra flush and non-petaloid; rudimentary pore-pairs only adapically.
• Periproct supramarginal; clearly visible in aboral view.
• Peristome circular, midway between centre and anterior; facing downwards and not sunken.
• Labral plate long and narrow, extending to second ambulacral plate. Sternal plates narrow and not much longer than labral plate; the two plates apparently more or less fused. Episternal plates not indented to posterior and offset.
• Aboral tuberculation fine and uniform.
• Well-developed peripetalous fasciole that passes well below the ambitus around the anterior.

Recent; Atlantic and Pacific; 1465 - 5200 m.

Aerope rostrata Thomson 1877, p. 211, by original designation.

• A. rostrata Thomson, 1877; Recent, North Atlantic
• A. fulva (Agassiz, 1881); Recent, East and North Pacific

Spatangoida, Hemiasterina, Aeropsidae.

Monophyletic.

Unmistakable by its highly distinctive shape. Distinguished from Sphenaster by its less laterally compressed form, more aboral periproct and more central peristome.

Mortensen, T. 1907. The Danish Ingolf-Expedition 1895-1896. Vol. 4, No. 2. Echinoidea, pt. 2, 200 pp. Bianco Luno, Copenhagen.

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