The species was conspecific with Incilius mccoyi until that species was described separately in 2011.
''Bufo intermedius''
In 2016, the enigmaticBufointermedius, known only from old museum specimens supposedly collected from Ecuador and long suspected to be related to some Mexican species, was found to be synonym of Incilius occidentalis. The decisive piece of evidence were the stomach contents that revealed two beetle species that do not occur in Ecuador.