Subspecies and Distribution. S. i. imperator Goeldi, 1907 — Brazilian Amazon into Peru, E of the upper Rio Purus, between the rios Purus and Acre; the distribution is probably more complex than is currently understood. S. 1. subgrisescens Lonnberg, 1940 — Amazon in W Brazil, SE Peru, and NW Bolivia, in Brazil E of upper Rio Jurua to the rios Tarauaca and Jurupari, in Peru W to the rios Urubamba and Inuya and S of Rio Tahuamanu to the Rio Muyumanu Basin in Peru and Bolivia. in Callitrichiade

Subspecies and Distribution. S. i. imperator Goeldi, 1907 — Brazilian Amazon into Peru, E of the upper Rio Purus, between the rios Purus and Acre; the distribution is probably more complex than is currently understood. S. 1. subgrisescens Lonnberg, 1940 — Amazon in W Brazil, SE Peru, and NW Bolivia, in Brazil E of upper Rio Jurua to the rios Tarauaca and Jurupari, in Peru W to the rios Urubamba and Inuya and S of Rio Tahuamanu to the Rio Muyumanu Basin in Peru and Bolivia.