In scientific classification, Synonymy is the existence of multiple systematic names to label the same organism.

When an organism is described for the first time, the organism is, at a minimum, placed within a genus and a species and where applicable, it may be named as a subspecies, variety, subvariety or form of that species.

A name can be identified as the first name or basonym by the author label. If the name used is the first one given to the organism, no brackets are used in the name, e.g. Acanthocalycium aurantiacum Rausch. If it is later decided that this name should change, the original author label is retained, but placed in parentheses, while the author(s) who defined the current name are added without parentheses.

Some examples:

  • Acanthocalycium aurantiacum Rausch - 1968
  • Echinopsis aurantiaca (Rausch) Friedrich & G.D.Rowley - 1974
  • Lobivia thionantha var. aurantiaca (Rausch) Rausch - 1987