The male and female have an abdomen mottled dark greyish brown and beige.
The head and thorax are dark reddish brown, and the legs have darker rings.
Male Austrarchaea griswoldi has a large bulb on its pedipalp, the leg-like appendage beside the mouth. Part of the bulb forms a rectangular, lid-like plate covering smaller structures. A broad, flattened plate also extends along its outer edge. In the described specimen, the bulb is much wider than 0.3 millimetres.
A 2024 study illustrated this species’ name-bearing male beside the newly described Austrarchaea andersoni. Both share a large bulb and a rectangular opercular plate. The authors distinguished them through bulb shape and the size and taper of the flattened sclerite, as well as differences in the slope of the posterior head region. The preserved male from Eungella thus contributed again to comparison with a spider from another rainforest.
An extinction-risk assessment has not been added yet.
Eungella National Park, where griswoldi is documented, is included in the Mackay Highlands management statement of 2013, extended in 2024. It provides for coordinating fire management, weed and feral-animal management, research and monitoring across parks and forests, with maintaining natural integrity and landscapes as a priority. These are regional directions for forests encompassing the spider’s documented habitat.