[3][4] The specific name acerus is Greek and refers to the absence of tubercles on the eyelid, heel, and tarsus.

[2][4] The snout is subacuminate in dorsal view and pointed or protruding in lateral profile.

The dorsum is black or dark grey; dorsal skin is smooth.

[2] Pristimantis acerus is known from the cloud forests of the Andes at elevations between 2,660–2,750 m (8,730–9,020 ft) asl.

[2] Likely threat to this species is deforestation caused by agriculture, logging, and human settlements.