Adult size 5.3 to 8.5 mm. Shell uniformly brown, including aperture and columella. Protoconch 1.3 whorls (only one protoconch seen). Teleoconch 4.0—5.5 whorls; whorls convex with distinct sutures. Spire 44-49% length of shell. Axial ribs and spiral cords over entire teleoconch; 25—31 axial ribs and 17-22 spiral cords on body whorl, with ribs being somewhat stronger than cords. Intersections of ribs and cords somewhat raised, can appear as weak beads anteriorly on body whorl; interspaces appear as round to rectangular pits. Axial ribs become weaker anteriorly on body whorl so that spiral cords appear more prominent. Spiral cord immediately below suture stronger than adjoining one and bordered by a subsutural groove that can be faint in some specimens. Axial ribs on both spire and body whorl broader than intercostal spaces. Four or five ribs nearest outer lip thinner and more closely spaced than others on body whorl. Outer lip with 6-13 denticles which extend no more than one tenth whorl into aperture. Apertural lirations lacking. Outer lip with small posterior sinus just below suture. Columella with four plications; one specimen with weak fifth plication.

Mitromica calliaqua differs from M. foveata in having finer sculpture that does not develop strong beading at the intersections of the axial ribs and spiral cords. Although there is some overlap, specimens of M. calliaqua have 25 to 31 ribs on the body whorl, whereas specimens of M. foveata rarely have more than 24, with a range from 12-28. Mitromica calliaqua differs from M. africana in having 1.3 versus 3.2 to 3.5 protoconch whorls and in tending to have fewer spiral cords on the body whorl (17—22 versus 21-28). It differs from M. esperanza in having fewer spiral cords (17—22 versus 24—32), fewer protoconch whorls (1.3 versus 1.7-1.9) and in generally being larger (5.3-8.5 versus 3.9—5.5 mm).

Type locality: Calliaqua, St. Vincent, Lesser Antilles, 13°08' N, 6l°12' W. Known only from Sr. Lucia, St. Vincent, and Petit Nevis, The Grenadines.