T. gratilla elatensis
As main difference
an adult Tripneustes gratilla
elatensis has fewer
primary spine tubercles on the
interambulacral plates, as they appear only in 1 of 2-3 plates, while in T. gratilla each interambulacral
plate has a primary tubercle. Another conspicuous difference is the colour. T. g. elatensis has in average
a lower number of plates. The diameter, formerly supposed to be lower in T. g. elatensis,
may reach the same dimension
as for T. gratilla (I found in Hurghada a specimen with 160 mm diameter). As I have been informed
by Dr. J. Dafni, a genetic-investigation is running to confirm either the status of a sub-species or to show as result even
a new species.
J. Dafni, A new subspecies of Tripneustes
gratilla from the northern Red Sea (Echinodermata:
Echinoidea: Toxopneustidae), Israel Journal of Zoology, Vol. 32, 1983, pp. 1-12.