Descriptions of this species are provided by VERDUIN (1984) and SEGERS ET AL. (2009), and the following description is based on the material examined by us.
Shell almost transparent, with 5 whorls in adult specimens reaching up to 2 x 1 mm. The body whorl occupies about 70% of the total height while the aperture nearly 35%. Sculpture of weak spiral furrows, mainly on the last whorl. The suture is not canaliculate but has a weak subsutural rim and a very slight subsutural depression which can be seen in the early whorls. Colour of the shell yellowish horny, with a whitish base and three rows of dark red spots on the last whorl.
Paucispiral protoconch with 1.25 whorls and about 320 µm in diameter (nucleus just over 100 µm). In the studied specimens its surface seems almost smooth

The shape, size and solidity of the shells resemble those of the type species C. semistriata. Nevertheless it differs from the latter by its paucispiral protoconch and the weaker sculpture. Its non-pigmented apex differentiates it from C. depicta. No significant differences were detected between shells from the Canary, Madeira and Selvagens islands. In addition to the many individuals with normal colour pattern consisting of three rows of reddish-brown squares, we found three banded shells on which reddish-brown squares become continuous. SCUDERI & AMATI (2012) compared C. picta and C. callosa to the Mediterranean C. galvagni (Aradas et Maggiore, 1844), and noted that both Macaronesian species have thicker shells, more flattened whorls and base, and lack an umbilical chink.

Recorded in Madeira (VERDUIN, 1984; SEGERS ET AL., 2009), Selvagens (WATSON, 1873; ALBUQUERQUE ET AL., 2009) and Canary Islands (El Hierro and Gran Canaria: VERDUIN, 1984; La Palma, Tenerife and Lanzarote: this paper). Known from intertidal down to 50 m in depth.