Melanophryniscus pachyrhynus is a species of toad in the family Bufonidae. It is known from São Lourenço do Sul in southern Brazil and from Uruguay. Populations in Uruguay were until recently considered a different species (Melanophryniscus orejasmirandai) and assessed as being vulnerable.[1]
Its natural habitats are subtropical or tropical seasonally wet or flooded lowland grassland, intermittent freshwater lakes, and intermittent freshwater marshes. It is threatened by habitat loss.