Jujubinus ruscurianus (Weinkauff, 1868)
Western Mediterranean and adjacent Atlantic.
Grazer and deposit feeder in the infralittoral.
Original taxon: Trochus ruscurianus. Synonym: kochi.
 
« Shell small for the genus (h: 4/5 mm); solid, generally slightly cirtoconoidal in shape. Protoconch of about one and a half whorls, smooth, globose. Teleoconch formed by 5/6 whorls, the two first ones convex; sculpture of 3/4 spiral grooves, separated by a more salient basal cord. The successive whorls are flat, crossed by 4/6 (mean 5) sub-spinal spiral cords, separated by interspaces of a smaller width than the cords, and crossed by very fine opisthocline growth-lines. In some specimens the cords progressively narrow into amplitude, generating more developed interspaces. The basal cord, weakly marked, becomes progressively more evident, so much so as to make the last whorl more or less dullly hinged to the periphery. » – M. Curini Galletti: “Note ai Trochidae: IX - Jujubinus ruscurianus, Bolletino malacologico XVIII, Milano 1982.

Young specimen collected at 2-3m deep, on leaves of Posidonia oceanica, Cap Dramont, Saint-Raphaël, Var, SE. France. 4mm.
« The last whorl is large, and makes up about 70% of the height of the spire. Base convex, imperforate, […] traversed by 6 ridges, finely furrowed, much thinner than the interspaces. Columella slightly oblique, mildly thickened in its lower third. Aperture subcircular, intensely pearly inside; external lip not thickened. Background color ocher-ferruginous; cords articulated in brown and white, sometimes in the form of irregular longitudinal flammules. Basal cords regularly dotted, pericolumellar area white. » – Ibid.

Subadult from 25-35m deep, Málaga, Andalucia, S. Spain. 4,45mm. Original pictures provided by J. M. Martin (ES).
(CC BY-NC-SA)
A rounded one from Cala de Mijas, Marbella, Málaga. 4,6mm.
Adult from 20m deep, Punta de la Mona, La Herradura, Granada, Andalucia. 5,3mm. Notice the yellow interspaces between the basal cords.
Same spot, with a slightly more rounded base. 3,5mm.
Same spot. 4,1-4,6mm.
Same spot. 3,8-4,6mm.
26m deep, Punta de la Mona. 3,5-4,5mm.

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