Spix's howler occurs south of the Amazon River in Brazil. In a studied small group, fruit made up much of the diet, and use of seasonally flooded forest changed with the season.
The IUCN taxonomic account distinguishes this species using a combination of skull and hyoid features and coat pattern.
Studies summarized by the IUCN assessment recorded groups of 2–9 and a fruit-heavy diet. Seasonal use of flooded forest was also reported.
An extinction-risk assessment has not been added yet.