The Bewani-Torricelli-Prince Alexander Mountains, are presumed to have been formed as an island arc in the Late Eocene-Early Oligocene.

[2] As with other mountain ranges in Papua New Guinea, the Bewani Mountains are home to many rare species of fauna and flora and is highly biodiverse.

The black sicklebill (Epimachus fastuosus) is a threatened species which is known from a few localities in the Bewani and Torricelli mountains.

[1] Fiwo, a subspecies of the tenkile (Dendrolagus scottae) tree-kangaroo, is thought to be endemic to the Bewani Mountains.

[3] Two frog species described in 2000/2001, Cophixalus bewaniensis and Choerophryne longirostris, are so far only known from the Bewani Mountains.