Echeveria microcalyx Britton & Rose, 1911
When Britton published Echeveria purpusii in 1905 he was unaware that this name had already been used in 1896 by K. Schumann for a quite different plant. That means E. purpusii Britton was an illegitimate name. The correct name for this plant is E. microcalyx Britton & Rose.