There are thirteen species in the genus[3] all are adapted to cold conditions,[4] and many are coloured for camouflage against rocky ground.

[5][6] The largest species Sigaus villosus can reach 48mm (body length of adult female).

[7] The taxonomy of New Zealand endemic grasshoppers was substantially revised by Bigelow in 1967, based mostly on female genitalia,[5] and again in 2023 using genetic data.

[3] The New Zealand radiation of cold-adapted grasshoppers is monophyletic but neither genetics nor morphology resolve distinctive genera, therefore it was suggested that all thirteen species be placed in the genus Sigaus.

[3] The genus Sigaus is distinguished from other Acrididae as flightless, silent acridids with short tegmina, crypsis colouration and endemic to New Zealand.