The Echinoid Directory

Habrocidaris Agassiz & Clark, 1907, p. 234

Diagnostic Features
  • Test small (less than 25 mm diameter), low and subconical, oral side flattened.
  • Apical disc large, dicyclic; genital plates pentagonal, ocular plates projecting and trapezoidal. Periproct opening central, subpentagonal, with five anal valve plates. Gonopores opening close to outer edge. Disc covered in small pustules.
  • Ambulacra trigeminate, with small pore-pairs, uniserially arranged to peristome.
  • Ambulacral plating not clear; all elements reacing the perradial suture adapically; possibly two elements united by primary tubercle at ambitus and below. Adoral plating simple.
  • A single perradila sphaeridial pit.
  • Interambulacral plates wide; primibasal plate present and prolonged with a median primary tubercle.
  • Aboral plates without primary tubercles, with small granules only, not forming clear rows.
  • On oral surface one primary tubercle on interambulacral plates, adradial in position subambitally.
  • Primary tubercles imperforate and non-crenulate.
  • Peristome large, plated; buccal notches more or less absent; no tag.
  • Spines flattened, triangular in cross-section.
Distribution
Recent, East Pacific, Caribbean.
Name gender feminine
Type
Podocidaris scutata Agassiz, 1880, p. 72, by original designation.
Species Included
  • H. scutata (Agassiz, 1880); Recent, West Indies.
  • H. argentea Agassiz & Clark, 1907; Recent, Hawaii.
Classification and/or Status
Euechinoidea, Echinacea, Arbacioida, Arbaciidae.
Remarks

Distinguished from Dialithocidaris by having just a single primary tubercle on interambulacral plates, not two, and by lacking rows of glassy pegs.

Agassiz, A. & Clark, H. L. 1907. Preliminary reports on the Echini collected in 1902, among the Hawaiian Islands, by the U. S. Fish Commission steamer “Albatross”, in charge of Commander Chauncey Thomas, U. S. N. commanding. Bulletin of the Museum of Comparative Zoology, Harvard College, 50, 231-259.

Agassiz, A. & Clark, H. L. 1908. Hawaiian and other Pacific Echinidi. Memoirs Harvard Museum of Comparative Zoology 34, 43-134, pls 45-59.

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