Taxonomy and Phylogeny
There are at least two subspecies of the eastern gorilla: the mountain gorilla (Gorilla beringei beringei) of the volcanic slopes of Rwanda, Uganda and eastern Democratic Republic of Congo; and the eastern lowland gorilla (Gorilla beringei graueri) of the lowlands of eastern Democratic Republic of Congo and Uganda. A small population from the Bwindi Impenetrable Forest in southern Uganda and adjacent areas in Congo differs genetically from the other subspecies, and is therefore often considered as a separate, yet undescribed, subspecies.
The eastern lowland gorilla and mountain gorilla were previously thought to be two of the three subspecies of one single species, the gorilla (Gorilla gorilla). However, genetic research has shown that the two eastern subspecies are far more closely related than the western subspecies: the western lowland gorilla (G. gorilla gorilla), which justified the separate classification. The two eastern subspecies are now classified as G. beringei.
Read more about this topic: Eastern Gorilla