Hylobates gabriellae Thomas, 1909 . Ann. Mag. Nat. Hist., ser. 8, 4:112.

TYPE LOCALITY: Vietnam, Langbian .

DISTRIBUTION: S Laos, S Vietnam, Cambodia.

STATUS: CITES - Appendix I; U.S. ESA - Endangered.

SYNONYMS: siki .

COMMENTS: Subgenus Nomascus . Separated from leucogenys by Groves and Wang (1989).