The Echinoid Directory

Heterocentrotus Brandt, 1835, p. 265

[=Acrocladia Agassiz & Desor, 1846, p. 373, type species Echinus trigonarius Lamarck, 1816 by subsequent designation of Pomel, 1883, p. 77; = Holocentronotus Gray, 1850, p. 37 (nomen vanum); = Heterocentrus Gray, 1840 (nomen nudum)]

Diagnostic Features
  • Test elliptical in outline, with long axis passing through ocular plate II and genital plate 4.
  • Apical disc dicyclic; periproct relatively small.
  • Ambulacra polygeminate, with anywhere from 9 to 14 pore-pairs to a plate. In the type species pore-pairs are usually arranged in a simple arc round the margin of the plate, but may be more irregular forming a double arc or broad irregular band.
  • All ambulacral plates with single large primary tubercle occupying most of the plate surface.
  • Interambulacral plates with single large primary tubercle with massive mamelon and thick boss at ambitus. There are flanking secondary tubercles on the adoral surface.
  • Peristome elliptical with feeble buccal notches.
  • Wide phyllodes developed adorally.
  • Spines very thick and dense; with three or more flattened facets. Never modified to scales or plates.
  • Secondary spines truncate and stubby.
Distribution
Miocene to Recent; Indo-West Pacific.
Name gender masculine
Type
Echinus mammillatus Linneus, 1758, by subsequent designation of Pomel, 1883, p. 77.
Species Included
  • H. mammillatus (Linneus, 1758); Recent, West Pacific.
  • H. trigonarius (Lamarck, 1816); Recent, West Pacific.
Classification and/or Status

Camarodonta; Echinoida; Echinometridae.

?Paraphyletic, (by exclusion of Colobocentrotus and Podophora with more derived aboral spine canopy).

Remarks

The elliptical test has the same axis of elongation as seen in Colobocentrotus and Podophora and is similar in most test features. It is distinguished from those two taxa by having pencil-like aboral spines rather than a uniform canopy of short button or tesselate aboral spines. It also has a single primary tubercle to each interambulacral plate as opposed to two or more subequal tubercles seen in those genera and in Zenocentrotus. Compared to Echinometra it has facetted primary spines and more pore-pairs to its ambulacral plates.

Brandt, F. A. 1835. Prodrome descriptionis animalium. Recueil des Actes de l'Academie Imperiel des Sciences, St Petersburg 1834, 201-276.

Mortensen, T. 1943. A monograph of the Echinoidea III.3. Camarodonta 2. Echinidae, Strongylocentrotidae, Parasaleniidae, Echionometridae. C. A. Retzel, Copenhagen.