Yunganastes mercedesae is a species of frog in the family Strabomantidae.

[2] It is named after Mercedes S. Foster, who collected the holotype and was acknowledged for her herpetological collection efforts in South America.

[3] Yunganastes mercedesae is a beautiful frog with a striking colour pattern: the dorsum is medium brown with irregular, light green splotches and some black marks, and black eyestripe and lip marks.

Based on three adult males and two adult females, males measure 42–52 mm (1.7–2.0 in) in snout–vent length, whereas females are much larger at 62–63 mm (2.4–2.5 in) SVL.

[4] Yunganastes mercedesae is a rare frog inhabiting Andean cloud forest at moderate elevations (1400–1950 m).