The impact of taxonomic change on the Amazonian palm flora

Although taxonomy is an evolving discipline, taxonomic change is rarely accounted for in macroecological studies. By tracking the history of species descriptions and synonymizations of Amazonian palms, we reveal shifts in species counts across space and time, the factors associated with taxonomic lumping, and the time needed to detect synonyms. The 175 Amazonian palm species known to date are the result of a gradual accumulation of new descriptions and a few distinct revision events that led to the recognition of approximately 800 heterotypic synonyms. Most of these were detected after the mid-1990s and caused an 80% decrease in species counts within just three decades. The time to detect synonyms ranged from 3 to 227 years. Species with a large population, widespread distribution and those described in early years were more frequently lumped. This suggests undetected synonyms inflate species richness unevenly across taxa and regions. These findings highlight the importance of taxonomic revisions for our understanding of biodiversity. Systematic efforts across lineages are needed to advance plant taxonomy, thereby strengthening ecological analyses and conservation assessments.