Heterocentrotus trigonarius Lamarck 1816

Family: Echinometridae

Order: Echinoida

Locality: Indonesia, 2008

Dimensions: 66 x 51 x 32 mm

I got this specimen without taxon, but it belongs clearly to the Echinometridae and according to the number of pore pairs it is probably Heterocentrotus trigonarius. However, in all my literature I cannot find any remark to such a bright lilac test colour (one could suppose that it is a fake). Thus, it is only a colour morph or is there another species beside H. mammilatus and trigonarius?

 

Already Th. Mortensen in his a Monograph of the Echinoidea, III.3, Camarodonta. II, Copenhagen, C.A. Reitzel-Publisher. 1943, page 424 discussed the possibility of sub-species and varieties, mainly caused by different forms and colours of spines. See the following citation:

 

Variation. Great variation obtains in regard to the shape, size and colour of the primary spines, as well as in the character of the secondary spines, whether pointed or truncate, flattened. So great is the difference between the extremes, that one must find it hard to believe that they can be one and the same species (the two figures on Pl. 8 of A. H. Clark's paper of 1931 give the difference between specimens with pointed or truncated secondary spines excellently). H. L. Clark, Op. cit. 1912, p. 379, pointing out the fact that "specimens from Mauritius are brown with distinct shades of green and orange-red on the primaries, while specimens from the Paumotus are deep purple, with very little variation except in shade", thinks that these extremes "will probably at some future time be designated as subspecies". But specimens from intermediate localities connect the two extremes, as Clark justly points out, and since there are no structural differences between them, judging from the material available to me, I do not think it justifiable to make subspecies, or even varieties, out of them. I may mention that at Mauritius specimens with carinate primary and pointed secondary spines were not found in the same localities-as specimens with cylindrical primaries and truncate secondaries, which would seem to indicate them to be different species. Still, I do not find any other character by which they may be distinguished. If we were to give these two forms varietal names, we would have to do the same with the purple-spined form from the Paumotus and other South Sea islands; but here again we find specimens with cylindrical and other specimens with carinate spines. And then specimens with huge club-shaped, greenish spines from Tahiti, -and a form from the Society Islands with dark greenish-olive cylindrical, but pointed primaries might equally well deserve variety names. I do not see anything gained by naming all these various forms, which in very many cases could not be recognized with only a fair degree of certainty, so I think it very much prefer-able, at least for the present, to name them all simply trigonarius. If we were to name them, the name violaceus Blainville (a manuscript name of Blainville adopted by Perrier, Op. cit., 1869, who describes the pedicellariae) would no doubt have to be used for the form with the purple spines.