The Echinoid Directory

Rhynchocidaris Mortensen, 1909, p. 5

Diagnostic Features
  • Test low and rather thin-plated.
  • Apical disc and peristome about 50% test diameter; more or less dicyclic; plates generally covered in tubercles. Ocular pores rimmed.
  • Interambulacra of relatively few plates (up to 9). Tubercles perforate and non-crenulate with sunken areoles. Scrobicular circle not differentiated from other secondary tubercles; plate outside areole uniformly covered in secondary tubercles with no naked interradial zone.
  • Ambulacra almost straight. Pore-pairs very small and highly oblique, the two pores separated by a narrow partition. The neural canal large and partially separated from the inner pore on adoral plates.
  • Primary and smaller secondary tubercle to each ambulacral plate. Pore zones not sunken.
  • No naked perradial zone or pits developed.
  • Peristome with few series of ambulacral plates; non-ambulacral plates confined to outer zone.
  • Primary spines long, cylindrical, with short collar and distinct neck. Shaft ornamented with irregular thorns and with dense and fine hairs in between.
  • Secondary spines clavate, erect.
Recent, Antarctic.
Name gender feminine
Rhynchocidaris triplopora Mortensen, 1909, p. 5, by original designation.
Species Included
  • Only the type species.
Classification and/or Status




Distinguished from Ctenocidaris by having pore-pairs with the neural notch in the perradial pore of each pore-pair partially or completely separated as a distinct perforation.

Mortensen, T. 1909. Echin. aus dem Deutsch. Sudpolar-Expedition 1901-1903. Deutsh. Sudpolar-Exped. 1901-1903, Band 2, p. 5

Mortensen, T. 1928. A monograph of the Echinoidea. 1, Cidaroidea. C. A. Reitzel, Copenhagen.