from what I understand, there are six Great Apes:
The Gibbon-a small ape resembling a ail-less monkey
The Orangutan
The Chimpanzee
The Bonobo- also known as the Dwarf Cimpanzee
The Gorilla
The Human.
Dianne Fossey was known for her work with the Mountain Gorilla.
Is the Mountain Gorilla the same species as the Lowland Gorilla, or are they a separate species like the Bonobo?
Traditionally, all Gorillas have been considered to belong to one species, Gorilla gorilla. More recent work has suggested that two separate species be recognized, but these do not correspond to the traditional distinction between Lowland (with Western and Eastern forms) and Mountain Gorillas.
This site provides some details.
What was formerly the Western Lowland Gorilla Gorilla gorilla gorilla is now considered by some to be a separate species, Western Gorilla (G. gorilla), including two subspecies, Western Lowland (G. gorilla gorilla) and Cross River (G. gorilla deihli) Gorilla.
The Eastern Lowland Gorilla (formerly G. gorilla graueri) is now included with the Mountain Gorilla (formerly G. gorilla beringei) in the species Eastern Gorilla (G. graueri), with subspecies G. graueri graueri and G. graueri beringei. The Gorillas of the Bwindi area may represent another subspecies of this group.
Note that the gibbons are not a single species, but comprise up to 13 species in several different genera.
Oops, that’s wrong. It should read:
The Eastern Lowland Gorilla (formerly G. gorilla graueri) is now included with the Mountain Gorilla (formerly G. gorilla beringei) in the species Eastern Gorilla (G. beringei), with subspecies G. beringei graueri and G. beringei beringei respectively.
This site says there are no less than three Gorilla species, though I think usually they are considered to be only one with subspecies.
No, look closer. That site is using the traditional classification with one species and three subspecies:
Eastern gorilla - lowland: Gorilla gorilla graueri
Lowland gorilla: - Gorilla gorilla gorilla
Mountain gorilla: - Gorilla gorilla beringei