3.3.4.1 Alouatta seniculus (Linnaeus, 1766)

Type: Inexistent or unknown.

Type locality: Cartagena, department of Bolivar, Colombia.

Common name: Colombian red howler.

This is one of the two species of howler monkeys originally described by Linnaeus (1766) in his genus Simia. It was originally believed that it was broadly distributed in South America to the north of the Rio Amazonas, but morphological and genetic analyses have yielded enough evidence to conclude that the howlers in this area belong to a species complex (see below) rather than to a single species. Hill (1962) recognized nine subspecies of Alouatta seniculus (seniculus, arctoidea, stramineus, insulanus, amazonica, macconnelli, juara, puruensis, and sara), most of which are considered valid taxa today; a couple are considered synonyms, and others have even been reclassified as full species (see below). The only taxon not recognized as valid is stramineus, the holotype of which is a female A. caraya (see Rylands and Brandon-Jones 1998). Here we recognize three possible subspecies of A. seniculus: A. s. seniculus, A. s. juara, and A. s. puruensis. Three more taxa formerly included as part of the seniculus group (A. arctoidea, A. macconnelli, and A. sara) are considered to be distinct species, based primarily on genetic information (see below). Unfortunately, genetic information is not available for the entire species group. Gregorin (2006) elevated A. s. juara and A. s. puruensis to the species level; however, we consider that more studies (particularly on their geographic distribution and genetics) are needed before categorizing these taxa as distinct species. Nonetheless, we present each subspecies separately to allow a better understanding of the variation already observed by Gregorin.