Mesomys occultus Patton, da Silva, and Malcolm 2000

Mesomys occultus Patton, da Silva, and Malcolm 2000, Bull. Am. Mus. Nat. Hist., 244: 194.

Type Locality: Brazil, Amazonas, Colocação Vira-Volta, left bank Rio Juruá on Igarape Arabidi, affluent of Paraná Breu.

Vernacular Names: Tufted-tailed Spiny Tree-rat.

Distribution: Central Amazon of Brazil.

Discussion: Although similar to and sympatric with hispidus the two can be differentiated by morphology, karyotype and cytochrome b sequences (Patton et al., 2000). It is not clear at this time whether ecaudatus should be included in hispidus or is a senior synonym of occultus . Karyotype has 2n=42 and FN=54.