Claim: Porthidium nasutum inhabits the Atlantic lowlands from Mexico, in the Pacific lowlands, it occurs in southwestern Costa Rica.
Evidence: Inhabits the Atlantic lowlands from Mexico (Tabasco and Chiapas) through Belize, Guatemala, Honduras, Nicaragua and Costa Rica to eastern Panama and northwestern Colombia. In the Pacific lowlands, it occurs in southwestern Costa Rica, central and eastern Panama, continuing on to northwestern Ecuador.