The rare new locally endemic species Anthocercis sylvicola T.D. Macfarlane & Wardell-Johnson is described and illustrated photographically. Anthocercis sylvicola is most closely related to A. genistoides Miers and A. anisantha Endl., but differing most obviously in the smaller green and purple flowers. It is the only member of the genus confined to tall open-forest. Although restricted, its distribution shows a marked discontinuity, a common situation for conservative, relictual high-rainfall taxa in the area. The species is of conservation interest owing to the small area of distribution and small number of plants and populations known. It is listed among conservation priority taxa for Western Australia. A revised key to the spinescent species of Anthocercis is presented.