The male has two pairs of rudimentary horns on the raised head region.
The head and thorax are dark reddish brown, and the legs have darker rings.
In the described male Austrarchaea karenae, the first-leg femur measures 3.17 millimetres, exceeding the 2.97-millimetre body length. A dorsal abdominal plate joins the ventral sclerites at the front and extends back to the first pair of humps. Each of the rear humps is covered by its own separate small plate.
This male was collected on 24 November 1997 in rainforest at 1060 metres on Queensland’s Windsor Tableland and became the name-bearing specimen in the 2012 paper. The researchers used microscopy to measure body parts to the nearest hundredth of a millimetre. Its carapace is 1.15 millimetres long and 2.49 millimetres high. The long foreleg segment and tall cephalothorax form specific features of this tiny male’s build.
An extinction-risk assessment has not been added yet.
The Mount Windsor National Park management statement of 2013, extended in 2024, provides directions for forests on the tableland where karenae was collected. It calls for continued rehabilitation of logged forest and grazed lands through monitoring and removal of pests and stock, development of a fire-management strategy, and long-term research on species of conservation significance. These are regional management directions for the spider’s documented area.