A Field Guide to the Snails of Lord Howe Island

148 Zonitoides arboreus Introduced species - small glossy snails Family Gastrodontidae Most Gastrodontidae are native to North America. They are small to medium-sized herbivorous snails, with smooth or radially striated, globose to discoidal shells and a long, narrow foot. The family Gastrodontidae was previously included within Zonitidae but is currently considered to belong to a separate superfamily, the Gastrodontoidea, along with Oxychilidae. Zonitoides arboreus (Say, 1817) Quick Gloss Snail Shell. Size: H = 2.1-2.6 mm, D = 4.3-4.8 mm. Colour: Pale golden brown. Shape: Subdiscoidal with a moderately raised spire; tightly coiled, whorls rounded; sutures strongly impressed. Sculpture: Shell glossy, shining, smooth. Aperture: Ovately lunate. Umbilicus: Moderately narrowly open. Animal. Body blue-grey with a white sole. Key distinguishing features. Pale, glossy shell, narrowly open umbilicus, impressed sutures. Smaller than O. alliarius . Habitat and occurrence . First recorded in 1971. Now with a widespread but patchy distribution across the island. Native to North America. Remarks. Zonitoides arboreus is a recognised orchid pest. 3 mm