The male has two pairs of humps on the back of its abdomen.
The head and thorax are dark reddish brown, and the legs have darker rings.
Male Austrarchaea thompsoni have a small body and slender, elongated legs. In the described male, the long femur of the first leg exceeds the combined body length of the cephalothorax and abdomen.
The male described in the 2012 paper measured 2.97 millimetres in total body length, while its first-leg femur measured 3.23 millimetres. This is one segment rather than the complete leg. Measuring body and leg parts separately documented the proportions of this small spider.
The specimen was collected near Devils Thumb, Queensland, on 10 October 1982. Geoff Thompson was among its collectors. The name thompsoni, published thirty years later, honours both his contribution to collecting this specimen and his continuing work documenting small rainforest animals.
An extinction-risk assessment has not been added yet.
The 2012 description considered information insufficient to assess the species’ conservation status. Its recorded collection area is in the Mossman Gorge section of Daintree National Park. The park is now jointly managed by an Aboriginal corporation and the state parks service. Official guidance asks visitors to stay on tracks to reduce vegetation disturbance and erosion. Alongside forest protection, surveys around the historical locality could help clarify the spider’s distribution and conservation needs.