Bauxitic insect pupal cases from northern Australia

Within the Weipa bauxite deposit of northern Queensland, Australia, are rare ovoid structures averaging 49 × 30 mm in size and of a similar composition to the surrounding bauxite. Comprised of a thin shell with an opening near one end, these structures encase ordinary bauxitic pisolitha and are referred to as ovate compound pisoliths. A small proportion of them are completely hollow and have no apparent opening into their chamber. Similar calcareous structures are found along the west coast of Eyre Peninsula, South Australia. These calcareous structures are interpreted to have been constructed by the larval stage of the weevil Leptopius duponti, for protection during pupation. The calcareous structures have a similar size and shape to bauxitic pisoliths, suggesting that ovate compound pisoliths may have been constructed by a similar organism, possibly belonging to the genus Leptopius.