Mirarissoina lata n. sp. Description holotype.- Shell small (3.3 mm), non-umbilicate, elongate- ovate, with 3½ smooth, narrow, transparent, pointed protoconch whorls ending in a "sinusigera notch"; transition to the teleoconch sharply demarcated; teleoconch whorls 5, moderately convex, covered by narrow, close- set, weakly opisthocyrt riblets (about 20 on the last whorl), varying from slightly opisthocline on the first teleoconch whorl to slightly sigmoid on the body whorl, crossed by finer spiral riblets, the intersections being microscopically tubercular. Base with a narrow, weak spiral fold along the axis. Aperture ovate, slightly flaring anteriorly, near the inner lip, and at posterior end constricted, ending in a narrow, deflected posterior sinus. The inner lip at this point incrassate, forming a moderately-developed swelling. Outer lip moderately incrassate, the apertural rim bent backwards, and crenulate by the end of the spral riblets. At the posterior end forming a small knob. Colour translucent white, with on the teleoconch whorls three narrow golden brown bands of about equal width; one just below the suture, the second just above the whorl's periphery, the third on the base.
Type locality.- WEST INDIES, GUADELOUPE: Grand Cul- de-Sac Marin; Vieux Bourg (16°23' N; 61°33' W); dredged in 130 m (Mission KARUBENTHOS Station GD06, 06.V.2012). MNHN 26382. Other material.- Etymology:Lata, Latin for wide, referring to the shell width.
Differential diagnosis.- Mirarissoina lata n. sp. differs from all its congeners principly in being wider, hence the name. It differs from the sympatric M. bermudezi (Aguayo & Rehder, 1936) (fig. 3) also in having more, and narrower protoconch whorls, a weaker basal rib, and in lacking the strong tubercule above the inner lip which is so typical of the latter. Instead, it has only a moderate, elongate swelling, deflecting the posterior sinus outwards.