Males and females have a strongly upright, neck-like region and bold abdominal markings.
In the described male and female, the abdomen has wavy brown rings and a single hump on its back.
Eriauchenus andrianampoinimerina occurs on vegetation above ground, with records extending from low-elevation forest to montane shrubland. Its documented habitat spans both height within vegetation and elevation on the landscape.
In December 2008, specimens were collected at 195 metres in Mikira forest north of Maroantsetra. A female and a juvenile came from vegetation five to ten feet, approximately 1.5–3 metres, above ground.
In February 2003, a male and a juvenile were collected in shrubland at 2,000 metres in Marojejy National Park. The 2018 revision brought these separate locality records together to document the range of environments in which the species had been found.
An extinction-risk assessment has not been added yet.
Madagascar National Parks identifies logging, clearing followed by fire, and hunting as major pressures on Marojejy as a whole. Surveys of this spider could include low-elevation forest and high-elevation shrubland, recording height above ground and vegetation conditions to clarify local habitat use.