Water pennies

Code QC370000

The extremely flattened, very broadly-ovate bodies of larval psephenids, in which most tergites are greatly extended laterally to completely conceal the head and legs in dorsal view, make this group instantly distinguishable from all other beetle larva. Even when somewhat ovate and flattened, the heads of other beetle larvae are always visible in dorsal view (for example, some Elmidae). Mature larvae range from 3-10 mm in length. Antennae 3-segmented, stemmata (5-6 pairs) closely clustered to form a single eye. Legs 5-segmented, the apical tarsungulus being short. Sternum of the 9th abdominal segment bears an opercular chamber into which a tuft of filamentous anal gills may be withdrawn. Urogomphi absent. Extended segments generally bear a marginal fringe of partially fused hairs.

Psephenidae (Polyphaga, placed in Byrrhoidea by Australian authors, Dryopoidea by American authors) are represented in Australia by around 15 species, all in the genus Sclerocyphon . Larval psephenids are streamlined animals which feed on algae on rocks in exposed positions with high energy flows. The adults are cryptic but have been observed flying above streams on hot days. They occur in eastern Australia, with one species recorded from the George Gill Ranges in central Australia.

References:

Brown, H.P. (1991) Psephenidae (Dryopoidea) pp. 395-397. In: Stehr, F.W. (ed.) Immature Insects. Volume 2. Kendall/Hunt Publishing Company, Dubuque, Iowa.

Lawrence, J.F. and Britton, E.B. (1991) Coleoptera. pp. 543-683. In: CSIRO, Insects of Australia. Volume 2. Melbourne University Press, Carlton, Victoria.