The Echinoid Directory

• Test small (less than 10 mm diameter in type species), low and subconical, oral side flattened.
• Apical disc large, dicyclic; genital plates pentagonal, ocular plates projecting and subtrigonal. Periproct opening small and central, circular, with four valve-like anal plates. Gonopores small, central. Disc covered in small pustules, sometimes connected by horizontal and vertical ridges giving a sculpted appearance.
• Ambulacra trigeminate, with small oblique pore-pairs, every third a little larger; all aboral tube-feet suckerless; uniserial throughout, no phyllodes developed adorally.
• Ambulacral plating not clear, probably arbaciid, as in Pygmaeocidaris.
• Interambulacral plates wide; primibasal plate present and prolonged with a single primary tubercle.
• Aboral plates without primary tubercles, covered in fine epistroma and peg-like pustules, forming vertical and horizontal bands; the adradial ones largest.
• On oral surface one primary tubercle on ambulacral plates and two on interambulacral plates; tubercles imperforate and non-crenulate.
• Sphaeridia: one or two at perradius, not in pits.
• Peristome about half test diameter.
• Spines rather short, flattened, with distal glassy cap.

Eocene, Europe, North Africa; Recent, Caribbean, Indo Pacific.

Podocidaris sculpta Agassiz, 1869, p. 258, by original designation.

• P. sculpta Agassiz, 1869; Recent, Caribbean.
• P. sibogae Mortensen, 1934; Recent, Malaysia.
• P. ornata Clark, 1912; Recent, Hawaii.
• P. mortenseni Lambert, 1911; Middle Eocene, France.

Euechinoidea, Echinacea, Arbacioida, Arbaciidae.

Monotypic.

Distinguished from Codiopsis by having much smaller, non-conjugate pore-pairs aborally, and by having a large adradial pustule on each aboral plate connected vertically by an epistromal ridge, much as in Coelopleurus.  In Coleopleurus primary tubercles extend aborally whereas they are confined to the oral surface in Podocidaris. 
    Arbaciella is very close indeed and Mortensen (1935) even noted the great similarity in the structure and arrangement of their spines.  The only difference between the two seems to be in the development of the primordial interambulacral plate which is prominent and extends interradially in Podocidaris but is not prolonged in Arbaciella.

Agassiz, A. 1869. Preliminary report on the Echini and starfishes dredged in deep water between Cuba and Florida reef by L. F. De Pourtalès, Assist. U.S. coast survey. Bulletin of the Museum of Comparative Zoology, Harvard College, 1 (9), 253-308.

Mortensen, T. 1935. A monograph of the Echinoidea II. Bothriocidaroida, Melonechinoida, Lepidocentroida and Stirodonta. C. A. Reitzel, Copenhagen