The genus name (coel = hollow, gyn = female) refers to the deeply sinuated stigmatic cavity. There are about 150 species of this mainly Indo-Malaysian genus that occur, usually at higher elevations.

The pseudobulbs of C. guamensis are large, 8 by 3 cm, and ovoid in outline; one or two stiff, lanceo-oblong, pleated leaves. The inflorescence originates between the leaves at the top of the pseudobulb. The faintly fragrant flowers are cream with a rust lip. The plant blooms during all seasons, and produces up to 12 flowers that open successively. Seed capsules are large and deeply ribbed. Ants are abundant in and around the plant.

C. guamensis needs light shade and quite a bit of moisture. It appears to be abundant on the branches of large trees on the high limestone ridges of Guam and Rota, but this habitat is very limited. The plant have been found on Guam, Rota and Palau.