A Field Guide to the Snails of Lord Howe Island

73 Hedleyoconcha addita Hedleyoconcha addita Iredale, 1944 Lord Howe Island Conical Pinwheel Snail Shell. Size: H = 5.6 mm, D = 7 mm. Colour: Pale golden-brown. Shape: Trochoidal with a high conical spire; whorls rounded with a keeled periphery; sutures flat. Sculpture: Smooth shell with little sculpture. Aperture: Roundly lunate. Umbilicus: Moderately narrowly open, partially concealed by reflected lip. Animal. Not known. Key distinguishing features. Conical shape, keeled periphery, flat sutures and lack of distinct sculpture. Habitat and occurrence. Only known from the summit of Mt Gower and ledges leading to Little Pocket; never collected alive. Very rare. Possibly arboreal (as are other members of Hedleyoconcha ). Remarks. This species has only been collected on three occasions, most recently in 2002. 5 mm