Austroaeschna sigma is a species of large dragonfly in the family Aeshnidae,[3] known as the sigma darner.

[4] It inhabits the upper reaches of small mountain streams in New South Wales and south-eastern Queensland, Australia.

[5] Austroaeschna sigma is a very dark dragonfly with pale markings.

It appears similar to the multi-spotted darner, Austroaeschna multipunctata,[4] which inhabits mountain streams in southern New South Wales and Victoria.

[5]