A Field Guide to the Snails of Lord Howe Island

54 Family Achatinellidae (Treesnails) Tornatellinops lidgbirdense (Iredale, 1944) Mt Lidgbird Miniature Treesnail Shell. Size: H = 3.7-4 mm, D = 1.6-1.8 mm. Colour: Dark golden brown (appearing near-black in live specimens). Shape: Elongately conical with a high spire and impressed sutures; whorls rounded. Sculpture: Glossy with distinct growth lines. Aperture: Subovate, with an elongate parietal lamella. Columella: Twisted; lamella present in juveniles. Umbilicus: Imperforate. Animal. Black. Key distinguishing features. Larger size; black body and darker shell colour; slightly less elongate shell than T. jacksonensis . Habitat and occurrence. Found only on the summit of Mt Lidgbird and Big Slope and Little Slope of Mt Gower. Rare. Living on rock faces. Remarks. The darker shell and body colouration of this species is probably due to selection pressure – living on a black basalt surface, dark individuals are better camouflaged. Malabar Kim’s Lookout Transit Hill Intermediate Hill Mt Lidgbird Mt Gower ▲ ▲ ▲ ▲ ▲ ▲ ● T. jacksonensis ● T. lidgbirdense