Males measure 17–22 mm (0.67–0.87 in) and females 20–24 mm (0.79–0.94 in) in snout–vent length. Dorsum is dark brown with diffuse greenish tint. It has an oblique lateral stripe extending to eye, cream with iridescent golden tint in colour and sometimes edged with brown or black.
Hyloxalus pulchellus is found in the inter-Andean páramos of northern Ecuador and adjacent Colombia (Nariño and Cauca Departments) and on the eastern slopes of the Andes from southern Colombia south in Ecuador to the headwaters of the Pastaza River. Colombian source does not include Nariño but does include Putumayo Department. Its altitudinal range is 1,590–2,970 m (5,220–9,740 ft) asl; at the higher end of this range it is the only frog species of this kind.
Male frogs call in or from under grass. The call is a buzz emitted 72 times during 4 minutes.
