Males and females have a single hump on the back of the abdomen.
The described male has a yellowish-brown abdomen mottled with brown. The described female is generally darker than the male.
Eriauchenus rafohy has an elongated neck-like structure and large jaws. Four projections on top of its head each carry a short spine. In the male holotype, total length was 4.41 millimetres and jaw length was 4.02 millimetres.
The 2018 study also examined body proportions in four males and six females. The femur of the first leg was 5.10–5.72 times the carapace length in males and 3.48–3.88 times in females. Mean lengths of that segment were 8.70 millimetres in males and 6.16 in females. In the specimens measured, the males had particularly long front legs relative to the carapace.
The species was named in honour of Queen Rafohy of Madagascar. Its male name-bearing specimen was collected in Ambohitantely Forest in April 2001. By comparing preserved specimens, their detailed morphology and body proportions, the authors described the new species in 2018. The study documented this tiny spider’s long front legs and jaws together with its collection locality and the origin of its name.
An extinction-risk assessment has not been added yet.
The 2018 description includes material collected in 2000–2003 in forests at Ambohitantely and near Andranomay. Maintaining habitat in these forests and checking present-day occurrence at documented sites would improve information for conservation.