Predatory shell drilling by two species of Austroginella (Gastropoda: Marginellidae)

Predatory shell drilling of bivalve mollusc shells is reported for the gastropods Austroginella johnstoni and A. muscaria from south-eastern Australia. This is the first record of this feeding behaviour in the family Marginellidae. The drill holes are circular and paraboloid, with a small inner penetration hole. The corroded nature of the aragonite crystals within the drill holes suggests a chemical dissolution drilling mechanism. No obvious accessory boring organ was located. The gastropods have subepithelial gland cells in the proboscis, a pair of small salivary glands and a large foregut gland. The latter has a duct bypassing the valve of Leiblein and joining the anterior oesophagus.