Splitting Butia archeri (Arecaceae) of Brazilian central highlands: new taxonomical and conservation insights for Butia

Originally described as an acaulescent species, the Butia archeri complex currently comprises two varieties. Butia archeri var. archeri has a wide distribution and both acaulescent and caulescent populations, while B. archeri var. diamantinensis is a microendemic represented only by caulescent individuals. Here, we compared the morpho-anatomy of two caulescent populations, one of each variety, with the acaulescent B. archeri from the typus locality (Lavras). Butia archeri from Lavras have shorter inflorescence axis and prophyll, similar-sized flowers, raphides in the pinnae, and accessory bundles surrounding the fibrous ring completely. Revolute bracts and fibres in the expansion tissue are exclusive of B. archeri var. diamantinensis, which, allied to the geographical isolation, clearly supports a new status and combination: Butia diamantinensis. The caulescence and lax rachillae allied to anatomical differences, show that Brasília’s population, formerly B. archeri var. archeri, is not B. archeri. Our results showed that the main diagnostic characters of B. archeri are lacking in the studied caulescent populations, warranting the rejection of the taxon’s amended descriptions. Furthermore, our study highlights the urgent need for further investigation into other taxa currently classified under B. archeri, particularly those facing extinction threats in the Cerrado. Here, we underpin the relevance of circumscriptions based on reliable characters to understand variable taxa, which impact conservation policies.