Description. — Shell small, fragile, slightly conical, almost smooth, with very isolated spiral striae. Protoconch typical for the genus, diameter about 150 µm. The teleoconch commences with slightly convex whorls and both parts of the whorl, which are not clearly separated from each other, having a similar covexity. The surface is smooth with only opisthocyrt growth lines; in the subsutural area the growth lines are strongly convex whilst the lower part has a prosocyrt weaker convexity. The well-defined opposedly curved growth lines are the only reference to the line of separation of the two parts of the whorls. Dimensions: The holotype measures 2.6 mm in height.
Distribution. — So far only known from New Caledonia (type locality) and the Philippines.
Etymology. — The name alludes that is as the previous, with even less differentiating characteristics.
Remarks. — This species is rather similar to M. modesta spec. nov.
Murchisonella modesta spec. nov. has a more elongate shell that is larger and narrower with more whorls, the suture is deeper and the angle formed by the spire is smaller and does not reach 30° (while in M. modestissima spec. nov. this angle is greater than 35°); the whorls in M. modesta spec. nov. increase more slowly in width (H/D ~ 3.6 compared to 3.0 in M. modestissima spec. nov. for the same number of whorls). On the last whorl the growth lines on the lower part of the whorl are more curved in M. modestissima spec. nov.