A Field Guide to the Snails of Lord Howe Island

74 Family Charopidae (Pinwheel Snails) Genus Mystivagor Iredale, 1944 Description. As for species (below). Remarks. Differs from all other genera in its reduced, globosely ear-shaped shell with a rapidly increasing last whorl and wide aperture. Mystivagor mastersi (Brazier, 1872) Slug-like Pinwheel Snail Shell. Size: H = 5.4-6.7 mm, D = 5.6-5.7 mm. Colour: Chestnut brown with cream-coloured, zigzagging flammulations. Shape: Globosely ear-shaped with a reduced shell, rapidly increasing last whorl and wide aperture; whorls and periphery rounded; sutures impressed. Sculpture: Protoconch with regular, widely spaced radial ribs; teleoconch with rugose surface but no distinct ribs. Aperture: Teardrop-shaped. Umbilicus: Absent. Animal. Body dark grey with paler grey sole. Key distinguishing features. Reduced, globosely ear-shaped shell with a broad aperture. Habitat and occurrence. Known from just a few localities, including South end Blinky Beach, Old Settlement Beach, Mt Lidgbird slopes and summit, Mt Gower summit. Rainforest and moist woodland, in litter. Very rare. Remarks. This species has only ever been collected in very low numbers and is currently listed as Critically Endangered. Some material may represent a second (undescribed) species, similar in appearance but around half the size. Given the paucity of the data we treat all specimens as belonging to the same species herein.