Overview

Hydraenids feed on algae in a variety of aquatic, riparian and littoral habitats, including streams, waterfalls, wet rock faces, ponds and ditches, marine rock pools, seabird nests, and inland salt lakes. Most adults are capable of breathing in water by means of a plastron formed by hydrofuge hairs on their ventral surfaces, but most larvae have no aquatic modifications. Exceptions occur in the genus Tympanogaster , where both larvae and adults live in the splash zone beneath waterfalls and larvae breathe through the spiracular tubes mentioned above. Hughleechia giulianii is a marine intertidal species, living in rock crevices and pools within the high tide splash zone.

Description

Small beetles with relatively inconspicuous antennae, often concealed within grooves beneath head and cavities between prosternum and pronotal hypomera, and well-developed maxillary palps, which may be as long as or longer than antennae. The segment preceding the antennal club usually forms a cupule like that in Hydrophilidae, but this is not always the case and sometimes it is the pedicel which is cupule-like. Larvae usually elongate and campodeiform, with well-developed legs, articulated urogomphi, and a pair of hooks on segment 10, but those of Tympanogaster species are more flattened, with paired lateral thoracic and abdominal plates and a pair of spiracular tubes projecting dorsally from between prothorax and mesothorax.

Distribution

The family is represented in Australia by two genera of Hydraeninae ( Hydraena and Limnebius ) and five described genera of Ochthebiinae ( Ochthebius , Gymnochthebius , Tympanogaster , Hughleechia and Meropathus ). [Newton 1985; Perkins 1980, 1981; Zwick 1977.]