Hyperolius pseudargus, also known as the Mette's reed frog, is a species of frogs in the family Hyperoliidae. It is endemic to south-central Tanzania and occurs in the Udzungwa Mountains and south to Njombe in the Southern Highlands. Male Hyperolius pseudargus greatly resemble Hyperolius argus but have less webbing between the toes and the male advertisement call is different. The vernacular name refers to Mette Westergaard, Danish biologist who collected the holotype and is the junior describer of this species.