C. arenaria

C. arenaria may refer to:
 * Carex arenaria, the sand sedge, a plant species
 * Catinella arenaria, the sandbowl snail, a small air-breathing land snail species
 * Cicindela arenaria, a ground beetle species native to the Palearctic Europe
 * Croitana arenaria, the inland sand-skipper, a butterfly species endemic to the Northern Territory and South Australia