A Field Guide to the Snails of Lord Howe Island

100 Innesoconcha aberrans Innesoconcha catletti Microcystidae (Tiny glass-snails) Innesoconcha aberrans Iredale, 1944 Black Face Glass-Snail Shell. Size: H = 4.4-5.1 mm, D = 6.9-8.1 mm. Colour: Golden brown. Shape: Depressedly trochoidal with an elevated spire; whorls flattened above and rounded below an angulate periphery; sutures weakly impressed. Sculpture: Shell with strong radial growth lines, not glossy; fine, faint to obsolete incised spiral grooves. Aperture: Ovately lunate; width greater than height. Umbilicus: Closed. Animal. Black. Key distinguishing features. Trochoidal shape with an elevated spire and angulate periphery; black body; only microcystid recorded primarily from rock faces. Habitat and occurrence. Upper slopes and summit of Mt Lidgbird, on basalt rocks. Rare. Remarks. This rare species is only known from a few specimens, but has recently been collected live at two sites on Mt Lidgbird. It is very similar in appearance to Melloconcha grata , another rare trochoidal microcystid from Mt Gower, but insufficient data exists to determine whether or not the two should be considered synonyms. 5 mm