Description. (in parentheses the data of the holotype) Shell small for the genus, height 5.6–6.15 (5.65 mm), width 2.75–2.95 (2.9 mm), solid, fusiform, biconic, slender, H/W=1.931–2.084 (1.948); a single, particularly slender specimen (Cala Calandra, Lampedusa Is.) with a H/W 2.218. Protoconch paucispiral shiny, slender, of 1.3–1.4 (1.4) convex whorl, d 0.20–0.225 (0.20 mm), Do 0.35–0.375 (0.35mm), DM 0.45–0.50 (0.50 mm), h 0.45 mm (0.45 mm), covered by large, densely arranged, subtriangular granules. Protoconch-teleoconch boundary well marked, slightly flexuose, opisthocline. Teleoconch of 4.4–5 (4.5) slightly convex whorls. Sculpture starting with 3–4 (3) spiral cordlets crossed by 13 (13) axial ribs on the first whorl, the abapical spiral more pronounced in the first two whorls, giving the spire a keeled outline. Additional spiral cordlets between the adapical ones and between the suprasutural one and the suture. Last whorl sculptured over the entire surface by 18–22 (18) strong spiral cordlets, flat, equidistant, of equal size, of which 4 (4) above the aperture and one partly masked by the suture. Axial ribs not present on the last 0.9 whorl. Two columellar folds, the posterior larger. Growth lines visible over the entire surface. Outer lip sharp, thickened internally with 7 denticles, the second or third posterior larger. Anal sinus shallow. Siphonal canal short, and wide. Coloration caramel in the background, with subsutural and basal areas lighter, a whitish stripe always present on the adapical spiral cordlet, more evident on the last whorl. Protoconch neatly lighter than the rest of the shell, first teleoconch whorls and aperture violet. Soft parts unknown.

M. tricolorata n. sp. is characterised by a peculiar chromatic pattern, and by the constant presence of a prominent abapical spiral cordlet, which gives the first whorls a keeled appearance. M. karpathoensis has fewer and larger nodules on the first whorls. M. mariottinii n. sp. has fewer spirals on the last whorl (14–18 v. 18–22 in M. tricolorata), a different outline with almost flat spire and a more blunt apex. M. mifsudi n. sp. has broader spirals with finer interspaces, and more robust columellar folds.

Type locality. Cala Calandra, Lampedusa Is., Central Mediterranean Sea, 30 m depth.
Other material examined. Italy: Capo Grecale, Lampedusa Is., 50 m, vii.2009, 2 sh (BA); type locality, 4 sh juv. (BA), 1 sh juv. (MO); Lampedusa Is., Punta Cappellone, Sicily, 4 sh (PC).

Known so far only from the type locality, Lampedusa Is., Central Mediterranean Sea. Recent. Empty shells in bioclastic sands, from 30–50 m. Found sympatric, often at different depths, with M. olivoidea, M. karpathoensis.