The taxonomic status of Bufo intermedius Günther, 1858: forensic entomology confirms what was long suspected from morphology

Bufo intermedius Gu ̈nther, 1858, has a complex taxonomic history, with the type series being reported from Guayaquil and the Andes of Ecuador. However, these specimens are not referable to any known South American bufonid species. We examined the type series and found, based on morphology, that the specimens likely represent a Mesoamerican species, as earlier authors had suggested. We further explored this possibility by analyzing the stomach contents of one of the syntypes. The unique combination of arthropods, particularly the presence of the beetle species Megalostomis dimidiata and Zygogramma signatipennis, confirmed that the Ecuadorian locality data are erroneous and that the type series was collected in Mexico. We here present that the types of Bufo intermedius are conspecific with the Mexican species Incilius occidentalis (Camerano, 1879) and propose a new synonymy between Bufo intermedius Gu ̈nther, 1858 and Incilius occidentalis (Camerano, 1879). An application has been made to the International Commission on Zoological Nomenclature to preserve prevailing usage of the junior name Incilius occidentalis for this widespread Mexican species.