Two subspecies of short-tailed emerald are recognized by the South American Classification Committee of the American Ornithological Society, the International Ornithological Committee (IOC), and the Clements taxonomy. They are the nominate C. p. poortmani and C. p. euchloris.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved July 24, 2022Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, J. A. Gerbracht, D. Lepage, B. L. Sullivan, and C. L. Wood. 2021. The eBird/Clements checklist of Birds of the World: v2021. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ Retrieved August 25, 2021 However, BirdLife International's Handbook of the Birds of the World includes as a third subspecies what the other three taxonomic systems treat as a full species, the green-tailed emerald (C. alice). In addition, subspecies euchloris has been treated as a separate species by some authors.
