Austramathes purpurea is a species of moth in the family Noctuidae. It is endemic to New Zealand and can be found throughout the North and South Islands but has yet to be recorded at Stewart Island. It inhabits native forest. This species might possibly be confused with A. pessota, however this latter species does not have the purple hue to the forewings. The larvae of A. purpurea feed primarily on māhoe but have been recorded as feeding on, and have been reared on, narrow-leaved māhoe. The larvae pupate in a silken cocoon on moss covered ground. Adults can be found on the wing during the months of March to January but mainly occur during New Zealand's late autumn, winter, and spring. Light trapping may not be the most efficient technique for collecting this species.

...