The Echinoid Directory

• Test bottle-shaped with strong posterior rostrum; thin-shelled.
• Apical disc with four gonopores. Compact, with single anterior plate bearing two gonopores (G2) and two postero-lateral plates each with a gonopore (ocular plates II and IV). Posterior genital plates rudimentary or lost. Posterior ocular plates far removed from remaining plates of apical disc.
• Ambulacra all similar with minute pores only.
• Anterior ambulacrum deeply sunken from ambitus adorally, forming a funnel-like opening to the peristome.
• Peristome subcircular and facing anteriorly into frontal groove.
• Plastron plating orthosternous; first sternal plate followed by a pair of symmetrical episternal plates.
• Plastron disjunct, with lateral ambulacral and interambulacral plates intercalated between the labrum and sternal plate. Labral plate often reduced.
• Posterior paired ambulacra also disjunct on oral surface, separated by plates of interambulacra 1 and 4 meeting along the midline.
• Scattered small tubercles distributed over the aboral surface.
• Periproct supramarginal, overarched by interambulacral plates forming a hood.
• Subanal fasciole present.

Recent; Pacific, Atlantic and Antarctic. As fossil from the Miocene of Japan.

Pourtalesia miranda A. Agassiz, 1869, p. 272, by original designation.

• P. miranda A. Agassiz, 1869; Recent, North Atlantic.
• P. jeffreysi Thomson, 1873; Recent, North Atlantic.
• P. alcocki Koehler, 1914; Recent western Indian Ocean.
• P. tanneri A. Agassiz, 1898; Recent, eastern Pacific.
• P. laguncula A. Agassiz, 1879; Recent, Japan Sea and Malaysia.
• P. hispida A. Agassiz, 1879; Recent, Antarctic.
• P. aurorae Koehler, 1926; Recent, Antarctic.
• P. debilis Koehler, 1926; Recent, Antarctic.

Holasteroida, Meridosternata, Urechinina, Pourtalesiidae.

Presumed monophyletic.

Differs from Helgocystis which is very similar in shape, in having the posterior ambulacra disjunct. Kikuchi & Nikaido (1985) described a fossil Pourtalesia from the Middle Miocene deep-sea deposits of Honshu, Japan.

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.1950. A Monograph of the Echinoidea. V.1. Spatangoida 1. C. A. Reitzel, Copenhagen.

Kikuchi, Y. & Nikaido, A. 1985. The first occurrence of abyssal echinoid Pourtalesia from the Middle Miocene Tatsukuroiso mudstone in Ibaraki Prefecture, northeastern Honshu, Japan. Annual Report, Geosciences, University of Tsukuba 11, 32-34.