The Echinoid Directory

Echinodiscus Leske, 1778, p. 195

[(=Echinoglycus Leske, 1778, p. 197 (nomen nudum); =Lobophora L. Agassiz, 1841, p. 64, non Curtis, 1825; =Tretodiscus Pomel, 1883, p. 71 (objective); =Tetrodiscus Lambert & Thiey, 1921, p. 323 (nomen vanum)]

Diagnostic Features
  • Test indented laterally; margin thin and sharp
  • Apical disc central;4 gonopores
  • Internal buttressing developed as dense honeycombed meshwork
  • Petals well developed; posterior pair shorter than the rest
  • Interambulacral and ambulacral zones similar in width at ambitus
  • Posterior ambulacra with long slit-like lunules or notches
  • All interambulacrum disjunct or virtually disjunct on oral surface; separated by enlarged first pair of post-basicoronal ambulacral plates
  • Basicoronal circlet pentastellate with interambulacral plates strongly projecting
  • Periproct oral, close to the posterior margin. Opening at outer edge of first pair of post-basicoronal interambulacral plates
  • Food grooves bifurcating at edge of basicoronals; highly branched distally
  • Tube-feet extending into interambulacral zones
Oligo-Miocene to Recent of the Indo-Pacific
Name gender masculine
Echinodiscus bisperforatus Leske, 1778, by subsequent designation of ICZN 1950
Species Included
  • E. bisperforatus Leske, 1778; Recent, Indo-Pacific
  • E. auritus Leske, 1778; Recent, Indo-Pacific
  • E. tenuissimus (L. Agassiz, 1847); Recent, Indo-Pacific
  • E. yeliuensis Wang, 1982; Early Miocene, Taiwan
  • E. formosus Yoshiwara, 1901; Middle Eocene, Taiwan
  • E. chikuzenensis Nagao, 1928; Oligo-Miocene, Japan
  • E. transiens Nisiyama, 1968; Oligo-Miocene, Japan
Classification and/or Status

Clypeasteroida; Scutellina; Scutelliformes; Scutellidea; Astriclypeidae

Presumed monophyletic


One of the most instantly recognizable genera because of its distinctive posterior lunules. The recent species E. auritus has narrow slit-like notches in the two posterior ambulacra but is otherwise similar. Differs from Amphiope in having short posterior petals and slit-like lunules or notches.

Mortensen, T. 1948. A Monograph of the Echinoidea IV.2 Clypeasteroida. C. A. Reitzel, Copenhagen.

Nisiyama, S. 1968. The echinoid fauna from Japan and adjacent regions, Part II. Palaeontological Society of Japan, Special Paper 13, 1-491, pls 19-30.

Wang, C.C. 1982. On the Early Miocene sand dollar Echinodiscus yeliuensis n. sp. from the Taliao Formation of Yeliu, northern Taiwan. Proceedings of the Geological Soceity of China 25, 150-157.