The Echinoid Directory

Histocidaris Mortensen, 1903, p. 22

[=Poriocidaris Mortensen, 1909, p. 53, type species Porocidaris purpurata Wyville Thomson, 1872; =Porocidaris Agassiz, 1872, p. 394, non Desor, 1858 ]

Diagnostic Features
  • Apical system with sparse spines around genital, ocular and periproctal openings, leaving large parts of genital plates naked.
  • Interambulacral columns composed of 6+ plates.
  • Primary tubercles perforate and rather strongly crenulate; areoles not deeply incised.
  • Scrobicular ring differentiated; tuberculation outside rather heterogeneous; confined to adradial and interradial margins.
  • Ambulacra narrow; with simple plating throughout; pore-pairs non-conjugate.
  • Peristome with biserial ambulacral zones and interradial platelets.
  • On inner surface of peristome each ambulacral plate with a distally directed prong.
  • Primary spines long and cylindrical, and either smooth or thorned; no cortical hairs; adoral spines short, curved and strongly serrated. Collar sometimes very long.
  • Secondary spines long and flattened; erect rather than adpressed around the base of the scrobicular spines.
Upper Cretaceous (Cenomanian) to Recent, worldwide.
Name gender feminine
Porocidaris elegans Agassiz, 1879, p. 198, by original designation.
Species Included
  • H. cenomanensis (Cotteau, 1855); Cenomanian, Europe.
  • H. mazzetti (Steffanini, 1908); Miocene, Italy.
  • H. mackayi Fell, 1954; Oligocene, New Zealand.
  • H. elegans (Agassiz, 1879); Recent, Indo-Pacific.
  • H. crassispina Mortensen, 1928; Recent, Australia.
  • H. mikasiensius (Yoshiwara, 1898); Recent, Japan.
  • H. variabilis(Agassiz & Clark, 1907); Recent, Hawaii.
  • H. cobosi (Agassiz, 1898); Recent, Galapagos Islands.
  • H. sharreri (Agassiz, 1880); Recent, off Nevis.
  • H. carinata Mortensen, 1928; Recent, Australia.
  • H. magnifica Mortensen, 1928; Recent, Philippines.
  • H. purpurata Wyville Thomson, 1872; Recent.
  • H. formosa Mortensen, 1928; Recent, Kei Islands.
  • H. recurvata Mortensen, 1928; Recent, Kei Islands.
  • H. nuttingi Mortesen, 1926; Recent, Cuba.
  • H. acutispina Mortensen, 1927; Recent, Indian Ocean.
  • H. denticulata Koehler, 1927; Recent, Indian Ocean.
  • H. longicollis Hoggett & Rowe, 1986; Recent, New Caledonia.
  • plus others...
Classification and/or Status

Cidaroida; Histocidaridae.

Presumed monophyletic.


Distinguished from Rhabdocidaridae by its non-conjugate pore-pairs. Clark (1907) argued that Poriocidaris (under the preoccupied name Porocidaris) was not worth distinguishing from Histocidaris at generic level, although Mortensen (1928) continued to maintain the two. Close to polycidarid genera such as Anisocidaris, from which it may be derived, but differing in having strictly uniform ambulacral tuberculation. In Anisocidaris every second or third ambulacral tubercle is enlarged.

Clark, H. L. 1907. The Cidaridae. Bulletin of the Museum of Comparative Zoology at Harvard College, 51, 165-230, pls 1-11.

Mortensen, T. 1903. The Danish Ingolf-Expedition 1895-1896. Vol. 4, No. 2. Echinoidea, pt. 1, 198 pp., 21 pls. Bianco Luno, Copenhagen.

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