Distribution Update, Advertisement Call, and Phylogenetic Position of the Malvasá Rocket Frog, Hyloxalus pinguis (Anura: Dendrobatidae)

Abstract. The Malvasá rocket frog, Hyloxalus pinguis, is a poorly studied species with a restricted distribution and limited data on its natural history. Its taxonomic status is also uncertain, with some researchers considering it to be a junior synonym of H. pulchellus. We explore the differences between H. pinguis and other species within the genus, update its distribution, including two new localities, describe its vocalizations, and provide the first genetic data and images in life. The species is known exclusively from disturbed areas within high Andean ecosystems in southwestern Colombia at 2,930–3,205 m above sea level (a.s.l.). All new localities were close to small creeks and wetlands. The vocalizations comprise a long train of single notes with 2–13 notes per call, 42–43 notes per minute, and a dominant frequency of 3,488–4,048 Hz, which differs from related species in the genus. Mitochondrial data suggest that H. pinguis is sister to H. delatorreae and not part of the H. pulchellus clade as previously suspected. Two specimens described as H. pulchellus are placed separately from the main H. pulchellus clade and require taxonomic revision, including a specimen from Monte Olivo (Ecuador) that groups with H. pinguis but is highly divergent (uncorrected pairwise distance of 3.9% for 16S). This could either be a divergent mitochondrial lineage of H. pinguis that would extend its range substantially to the south or be an undescribed taxon in need of further study. Overall, the mitochondrial phylogenetic reconstructions, genetic distances, and distinct vocalization calls suggest that H. pinguis is a valid species and not a junior synonym of H. pulchellus, and its small known distribution make it a conservation priority. Further systematic research on Hyloxalus is needed, including the collection of nuclear genetic data, to fully understand this understudied genus that likely harbors additional undescribed diversity.