A new dwarf palm from the campo rupestre: another piece of the Syagrus evansiana complex (Arecaceae)

Background and aims – In the Espinhaço Range, the campos rupestres harbour many endemic acaulescent Syagrus. Populations assigned to Syagrus evansiana include geographically and ecologically distinct populations. We reassessed the two populations used in the original circumscription of S. evansiana and revealed that they represent distinct species.

Material and methods – We compared morphological and anatomical characters from field collections of both populations. The pinnae anatomy was studied using light microscopy of free-hand cross sections. A diagnostic comparison with other members of the S. evansiana complex is provided, together with a distribution map.

Key results – Syagrus montana sp. nov. resembles S. evansiana but differs in leaf size, inflorescence architecture, and flower arrangement. Syagrus montana shows flowers only in triads, whereas S. evansiana frequently bears tetrads and pentads. Additional diagnostic traits include indumentum on the pistil of the flowers in pre-anthesis, staminode shape, fruit and endocarp size, and several pinnae anatomy characters.

An accessory vascular bundle within the expansion tissue is recorded only in S. evansiana, first recorded for the genus. Conclusion – Morphological and anatomical evidence, together with geographic isolation and habitat differences, supports recognition of Syagrus montana as a new species. Syagrus evansiana possess rare and exclusive morphological and anatomical characters.

Our results highlight the need to reassess other poorly studied populations currently assigned as S. evansiana. In addition, the data presented here corroborate the Espinhaço Range and its disjunctions as one of the centres of diversity of Syagrus. The discovery of this new species reinforces the uniqueness of the local flora and its classification as a priority area for conservation.