Shell depressed globular, with 4,25-5,25(moderately) convex whorls. At the beginning of the body-whorl the periphery is regularly rounded or (rarely) slightly angular; only juvenile shells of less than four whorls have a prominent keel. The aperture is rounded or (somewhat) elliptical, without or with an indistinct columellar angle below; the outer lip is not clearly thickened inside. The umbilicus is narrow but relatively broader than in T. pisana and not obscured by a reflected columellar lip. At the type locality the shells are much less fragile than they are in the Moroccan populations, where very thin, somewhat transparent specimens may occur. The shells are silky because of the (very) prominent microsculpture. Usually the light brown spiral lines and spirally arranged dots are not strongly contrasting with the whitish to creamy white background colour of the shell. The aperture may be vivid pink or purple inside, with the outside pattern (vaguely) shining through. Width 15.0-26.7 mm; height 10.7-18.6 mm.

T chudeaui differs from T. sacchii by (1) the prominent microsculpture, giving the shell a silky gloss, (2) the relatively larger, more circular aperture, less descending in front, and (3) the peristome, which is hardly or not thickened inside. The character (2) is most conspicuous in the Moroccan populations, which come nearest to the range of T sacchii.
T chudeaui can be distinguished conchologically from T. p. pisana by (1) the microsculpture, (2) the slightly less narrow umbilicus, and (3) the much less brightly contrasting colours.

T chudeaui is known from along the coastal road, 11.5 km W. of the Oued Chebeica, in the extreme southwest of Morocco, southwestward in the coastal area to Nouadhibou in W. Mauritania, at the southern border of Western Sahara.