In addition to the taxonomic treatment of Specklinia and similar pleurothallid genera, segregate taxa are recognized within the large genus Masdevallia. New orchid taxa are validly described for the first time, and other nomenclatural changes are validated within these Neotropical Orchidaceae.

From among the subgenera of Masdevallia are established the new genera Acinopetala, Alaticaulia, Buccella, Byrcella, Fissia, Luzana, Megema, Petalodon, Pteroon, Regalia, Reichantha, Spectaculum, Spilotantha, Streptoura, Triotosiphon, and Zahleria.

The polyphyletic genus Specklinia is dismembered, with the ten new segregate genera Dondodia, Gerardoa, Incaea, Lomax, Muscarella, Panmorphia, Ronaldella, Sarcinula, Sylphia, and Tridelta. Five new species are described as Muscarella rojohnii, M. werneri, M. xyloura, Specklinia ordinata, and S. pectinifera.

Miscellaneous new taxa appear in the pleurothallid genera Acianthera, Acronia, Arthrosia, Colombiana, Crocodeilanthe, Dracula, Dryadella, Loddigesia, Masdevallia, Myoxanthus, Ogygia, Platystele, Porroglossum, Restrepia and Trichosalpinx. New genera include Arthrosia, Loddigesia, and Ogygia. New species include Acianthera rinkei, Acronia lynniana, A. pyelophera, A. tobarii, Arthrosia freyi, Crocodeilanthe suinii, Dracula saulii, Dryadella marilyniana, Myoxanthus werneri, Platystele tobarii, Porroglossum marniae, P. parsonsii, P. sijmii, Restrepia persiciana, and Trichosalpinx jostii.

Seven new species, three among the new generic segregates for Masdevallia, include Alaticaulia royi, Luzama gemmula, Masdevallia gastrodes, M. ivanii, M. magaliana, M. nijhuisiae, and Spilotantha ferrusii.

A color frontispiece is included, with 681 plates of black and white line art by Carl Luer.