Minute marsh-loving beetles

Code QC350000

Body elongate and subcylindrical, length less than 5mm when mature. Limnichid larvae have short, 3-segmented antennae, segment 3 with an apical spine. Stemmata (5-6 pairs) very widely separated. Examination of the mouthparts is necessary to separate limnichids definitively from heterocerids in the key - heterocerids have well developed mandibula mola, limnichids do not; limnichids have 4 segmented maxillary palps, whilst those of heterocerids are 3-segmented.

Legs are short and 5 segmented, the apical segment forming a single tarsungulus (claw). Terminal abdominal segment pygopod-like, sternum of segment 9 either forming a feeble operculum or appearing to constitute a 10th abdominal segment. Body often covered with thick setae. Abdominal and anal gills absent (with the exception of Hyphalus , which has anal gills for living submerged in the interstices of intertidal coral reefs). Urogomphi absent.

Limnichids (Polyphaga, placed in Byrrhoidea by Australian authors, Dryopoidea by American authors) occur on intertidal coral reefs and in a variety of riparian situations where the larvae live in sand, mud or leaf litter, apparently feeding mostly on decaying vegetable matter. Adults are found on or in mud at the margins of ponds and streams. Around 30 species, few of which have been formally described, occur in Australia.

References:

Brown, H.P. (1991) Limnichidae (Dryopoidea) pp. 401-402. 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.