A new species of Indo-West Pacific jawfish, Opistognathus rufilineatus, recently discovered at Triton Bay, Bird’s Head Peninsula, Indonesia (western New Guinea) is described. Two specimens were collected in April 2006 and color photographs and observations of other individuals were made in 2007 during biodiversity surveys conducted by Conservation International. One of at least 25 new species of fishes obtained from the area, the new jawfish is described here to help call attention to the special conservation significance of the Triton Bay type locality that is currently under consideration as a marine protected area. The new species is one of more than 20 undescribed Indo-Pacific jawfishes of the genus Opistognathus under study by the first author. It is distinguished from all other Opistognathus by having uniformly pigmented fins, sides of body with narrow red-brown stripes, outlining each yellow-tan lateral scale row, and cheeks with a few small scattered, dark, brown spots and narrow, short lines.