In the described male and female, the head and thorax are dark reddish brown.
The described male and female have an abdomen mottled greyish brown and beige, with three pairs of humps on its back.
Austrarchaea platnickorum has been collected in rainforest and adjacent snow-gum woodland, in elevated litter under tussocky snow grass. The described male’s head reaches its highest point near the middle and slopes gently backward. Its carapace measured 2.38 mm high and 1.15 mm long, producing an elevated outline within these small litter refuges.
The 2011 revision’s types were collected at Banksia Point, New England National Park, on 18 April 2010 at 1,491 metres. Collectors sifted elevated litter beneath grass tussocks in Nothofagus rainforest and adjacent snow-gum woodland. One male, one female and one juvenile were genotyped. Eight diagnostic COI/COII nucleotide differences distinguished them from the other taxa examined, linking habitat records, morphology and genetic evidence.
An extinction-risk assessment has not been added yet.
In New England National Park, pests and weeds affect ecosystems. NPWS describes risk assessments for emerging invasive plants including cats-claw creeper and cherry guava, alongside continuing restoration and bush-regeneration activities. These park-wide activities help maintain forest habitat.