Males and females have a single hump on the back of the abdomen.
The described male has a yellowish-brown abdomen mottled with greyish brown. The described female has a generally darker abdomen without a clear pattern.
Male Eriauchenus rangita have a tiny projection on the pedipalp beside the mouth that appears three-branched when the palp is unexpanded. A complex shape is contained within a very small part of this millimetre-sized spider.
The 2018 description gives this projection a broad, transparent, unsclerotized base and two sclerotized terminal processes. One is forked and the other is not, producing its three-branched appearance.
The male holotype was collected at Ambohimanga village northeast of Antananarivo in July 1992. Microscopic examination and illustrations documented structures beside the mouth that help distinguish similar species alongside external body features.
An extinction-risk assessment has not been added yet.
The examined material includes specimens from montane rainforest near Itremo. Kew reports forest restoration, fire management and fire-data research in the Itremo region. Repeated surveys of historical collecting localities and surrounding forest vegetation and dead foliage could clarify this spider’s occurrence.