Order Megaloptera (Alderflies, dobsonflies)

Code QM019999

Stream-dwelling megalopteran insects, in Australia confined mainly lotic conditions in the eastern part of the continent, though with a single species known from the south-west of Western Australia. Abdominal segments 1-8 carry tapered, unsegmented gills and there are paired cerci but no caudal filament (cf. Sialidae).

Larval Corydalidae might be confused with a whirligig beetle ( Coleoptera: Gyrinidae ). The major external difference between Corydalidae and Gyrinidae is that the former carries one pair of gills on each of segments 1-8 whereas the latter carries one pair on each of 1-8 plus two pairs on segment 9. The gills of Gyrinidae typically are fringed with setae, unlike the bare gills of Corydalidae. If confirmation is required, the labrum and clypeus are distinct in megalopteran larvae but fused as a single sclerite in gyrinids, and megalopteran larvae have a 3-segmented not a 2-segmented labial palp.

The Australian Corydalidae all belong to the subfamily Chaulodinae, and are placed in two genera. Archicauliodes and Protocauliodes . Apart from one Western Australian species of Archicauliodes ( cervulus ), all taxa are eastern, with distributions from tropical north-east Queensland to eastern Victoria. Corydalid larvae are predatory on other stream macroinvertebrates.

References:

Theischinger, G. (1983) The adults of the Australian Megaloptera. Aquatic Insects 5 : 77-98.

Theischinger, G. (1991) Megaloptera. pp. 516-520. In: CSIRO, Insects of Australia . Volume 1. Melbourne University Press, Carlton, Victoria.