A new spiny frog of the genus Pristimantis (Anura, Strabomantidae) from the eastern slopes of the Ecuadorian Andes

A new species of rain frog from the upper montane forest of the eastern Andes in the upper Pastaza watershed, Ecuador is described. Pristimantis fergusoni sp. nov. is characterized by its short snout, conical tubercles on upper eyelids and heels, combined with a scarlet colored belly in females. These unique traits differentiate the new species among other Pristimantis of upper montane eastern Ecuadorian Andes. Phylogenetic analyses support its validity and place it within a clade nested with other tuberculated species occurring along the Andean slopes. Pristimantis fergusoni sp. nov. is currently known from only two close localities (Cerro Candelaria and Chamana Reserves) at elevations between 2972 and 3200 m elevation, within the Llanganates-Sangay Ecological Corridor. Data Deficient IUCN status is proposed until new information is available. Individuals were observed at night perched on vegetation in herbaceous and arbustive vegetation of upper montane forest. This discovery contributes to a growing body of evidence identifying the upper Pastaza valley as a hotspot of amphibian endemism and diversification. With this addition, 30 strabomantid species are described for this region in the last decades, underscoring its conservation importance. This discovery highlights the urgent need for integrated taxonomic efforts combining fieldwork, morphology, and molecular data to resolve complex evolutionary relationships within the megadiverse genus Pristimantis, especially in underexplored high-elevation habitats of the tropical Andes. Finally, we provide an updated phylogeny for this clade that clarifies its evolutionary relationships.