Amto–Musan languages

Amto–Musan is a language family of two closely related but not mutually intelligible Papuan languages, Amto and Siawi, of the Sandaun Province of Papua New Guinea. Amto–Musan was left unclassified by Ross (2005) (see Papuan languages#Ross classification) due to lack of data; Wurm (1975) had posited it as an independent family. The family has typological similarities with the Busa language isolate, but these do not appear to demonstrate a genetic relationship.