There are five humps on the back of the abdomen.
In the described male and female, the head and thorax are dark reddish brown, and the legs have darker rings. The abdomen is mottled greyish brown and beige.
Male Austrarchaea monteithi have a short brush of accessory hairs on the front of the jaws, while the described female lacks these hairs. The sexes share their general abdominal form but differ at the mouthparts.
The species honours Geoff Monteith, who first discovered it in the Gibraltar Range. The examined material includes a juvenile he collected on 30 March 1980. In April 2010, a male, a female and two juveniles were collected near Richardsons Creek at 1,061 metres.
The 2011 revision described the species using these specimens. Two mitochondrial genes were examined in the female and two juveniles, providing sequence differences that distinguished the species from other sampled taxa alongside morphological evidence.
An extinction-risk assessment has not been added yet.
The 2021 fire-impact report proposed the species as a candidate for conservation assessment. Analysis combining fire overlap with ecological traits raised concerns about fire susceptibility and recovery. Repeated surveys at known rainforest sites, including suspended litter, could help track occurrence.