Original taxon: Donax castaneus. Synonym: pusilla Philippi.
« D. with a strong, glossy, chestnut-coloured shell, furnished with a few irregular, transverse, antiquated ridges, or wrinkles; one single ray of the same colour, but darker, runs from the beak to the opposite margin, in a curved direction, and divides each valve nearly in equal parts; from this to the posterior end the colour becomes pale; umbo obtuse, rather inclining to the anterior, or longest side. » – G. Montagu: Testacea Britannica part II, London 1803, p.574.
Above: washed ashore specimens, Praia da Figueirinha, in the southwest of Setúbal, SW. Portugal. Original picture provided by F. André for iNaturalist – (CC BY-NC).
Montagu: « Inside of the same colour, smooth and glossy, with a small trace of the ray at the margin; hinge very strong; teeth, one very large, and one small, in each valve; no lateral teeth… » – A young specimen from 4-5m deep, La Isleta, Almería, Andalucia, S. Spain. 3,9mm.
« …cicatrix broad, running from the anterior side one third across the shell, in a transverse direction, from which continues a marginal line almost to the opposite side; margin plain. » – Ibid. Same spot. 3,6mm.