From extensive Chimanta Massif collections, this species seems constantly (albeit weakly) separable from C. coriacea Gleason by its glabrous (except for the toral region) hypanthium and young leaf surfaces (except the margins), as well as by the calyx lobes glabrous on the back. C. montana has moderately to densely glandular-puberulous hypanthia, young leaves, and calyx lobes. No other vegetative or reproductive criteria serve for separation. The type sheet of C. montana consists of six sprigs, of which the upper three are C. coriacea and the lower three (including the holotype) are C. montana. The two species are known from the Chimanta Massif by the following collections:
C. coriacea—Wurdack 34171, 34206, Steyermark & Wurdack 627, 722, 740.
C. montana—Steyermark & Wurdack 447, 542, 723, 741.