Description: Rab (Croatia), 19/05/2011, depth -5 m, diameter cm 17
Normally it reaches a diameter of 9-12 cm and exceptionally it can measure up to 18 cm. Every superomarginal plates is equipped with one strong spine, usually sharp but irregularly shaped, slightly flattened laterally, often yellow or orange but rarely off white.
It is distinguished from Astropecten bispinosus mainly for the superomarginal spines far from the inside edge of plates and they leave on top, on the base of them, a small bare area. Another important Astropecten platyacanthus’s feature is that the superomarginal plates are laterally, on vertical face, covered with scales and small spines rather than nude. Moreover, it is different because it has smaller, irregularly shaped, laterally flattened (rather than clean conical spine) superomarginal spines and because it has average less superomarginal plates on each arm. In addition, on average Astropecten platyacanthus has a central disc larger, a darker oral side and a small red point in the point of arms have.
Author: Pillon, Roberto ()
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Astropecten platyacanthus (Philippi, 1837)