Revision of the orchid genera Chrysoglossum, Collabium, Diglyphosa, and Pilophyllum (subtribe Collabiinae)

This article contains a taxonomic revision of four orchid genera of the subtribe Collabiinae: Chrysoglossum (4 species), Collabium (11 species), Diglyphosa (2 species), and Pilophyllum (1 species). Three species are described as new: Chrysoglossum ensigerum, Collabium acuticalcar and Collabium carinatum. Chrysoglossum halbergii, Ch. maculatum, Ch. gibbsiae, and Ch. cyrtopetalum are reduced to Chrysoglossum ornatum. Diglyphosa macrophyllum, D. celebica and D. elmeri are reduced to Diglyphosa latifolia. Keys to the genera and species are given. Synonymy, descriptions, colour notes, distribution, habitat notes, and detailed illustrations are given for the genera and species.