The Echinoid Directory

Almucidaris Blake & Zinsmeister, 1991, p. 632

Diagnostic Features
  • Test subconical with raised apical disc; plating relatively thick.
  • Apical disc more than 80% test diameter; subconical. Dicyclic; genital plates identical in size; uniformly covered in dense granules. Ocular plates greatly reduced and periproctal zone relatively small.
  • Sexually dimorphic; females with large brood chambers developed in the five genital plates.
  • Interambulacra with 5 plates in a series. Primary tubercles perforate and non-crenulate; areoles circular and incised. Areoles separated on all plates. Mamelons becoming larger adapically.
  • Scrobicular tubercles differentiated; extrascrobicular zones narrow with just a single band of secondary tubercles and granules on ambital plates.
  • Ambulacra narrow and sinuous. Pore zones incised; pore-pairs narrow, oblique, non-conjugate and with narrow interporal ridge.
  • Perradial zone with marginal series of primary tubercles and inner series of smaller secondary tubercles.
  • Peristome smaller than apical disc; plating unknown.
  • Primary spines unknown; secondary spines flattened.
Upper Cretaceous (Maastrichtian); Antarctic and Spain.
Name gender feminine
Almucidaris durhami Blake & Zinsmeister, 1991, p. 632, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

Cidaroida; Cidaridae; Cidarinae.



This beautiful little sea urchin is unmistakable because of the highly distinctive brood pouches developed in genital plates of females.

Blake, D. B. & Zinsmeister, W. J. 1991. A new marsupiate cidaroid echinoid from the Maastrichtian of Antarctica. Palaeontology 34, 629-635.