One hundred years of solitude: The rediscovery of Pristimantis ruidus (Anura, Strabomantidae) in the southern Andes, Ecuador and its phylogenetic relationships

Abstract

We report the rediscovery, a century after its last record, of two specimens of Pristimantis ruidus from approximately 6 km northeast of its type locality, in a montane forest from the western Andes of southern Ecuador. This species, described by John D. Lynch in 1979, based on specimens collected in 1922 by George H. Tate, was previously known only from the type series, all specimens originating from a single locality (Molleturo, Provincia Azuay, Ecuador, 2317 m elev.). The rediscovery occurred in November 2022 in the Reserva de Conservación Quitahuaycu, Molleturo Parish, Azuay Province. The two specimens, both females, are characterised by rough skin with numerous rounded low warts and tubercles on their dorsum, a W-shaped occipital fold, tympanum and tympanic ring not externally visible and by the lack of cranial crests, characters that correspond with the description of the holotype. We evaluate the phylogenetic relationships, based on two mitochondrial genes (12S and 16S rRNA) and one nuclear gene (RAG-1). These analyses reveal Pristimantis ruidus as a member of the subgenus Huicundomantis, being most closely related to P. philipi, a species with a distribution restricted to the paramo of the same mountain region (Macizo del Cajas). Pristimantis ruidus co-exists with Pristimantis jimenezi, three additional species of Pristimantis and one Noblella with uncertain taxonomic status. This rediscovery underscores the urgency of implementing effective conservation and monitoring measures for the few remnants of the original ecosystems from western Ecuador, which face ongoing anthropogenic threats and harbour a diversity that remains insufficiently studied.