Females have a long, neck-like region with only a weak constriction separating it from the head.
The described female has a beige abdomen mottled with brown and bearing tufts of white hairs. The legs are light brown with darker rings.
Eriauchenus milajaneae has four small spines on top of its head. The anterior median eyes sit on a large bulge, and a short downward-pointing spine occurs near the base of each long jaw. In the 2.33-millimetre female holotype, jaw length was 2.03 millimetres.
The name published in 2018 carries a wish for a future encounter. It honours Mila Jane Macaulay, with the authors expressing the hope that she would one day visit Andohahela and find this spider. Naming an existing specimen also became a way to look forward to someone meeting it in the forest.
The female holotype was collected during 21–25 January 2002. To distinguish it from similar species, the researchers compared internal structures as well as external form. In this female, the posterior part of a hardened internal genital plate has a broad rectangular extension. Its microscopic characters and the origin of its name were documented together when the tiny spider was described as a species.
An extinction-risk assessment has not been added yet.
Col du Sedro in Andohahela National Park was the only confirmed locality reported in the 2018 description. Maintaining its forest habitat and examining additional specimens from surrounding areas would help improve information for conservation.