A new endemic and critically endangered species of Butia (Arecaceae) with comments on morpho-anatomical novelties in the genus

Butia buenopolensis, a new dwarf Arecaceae species, is described. Butia buenopolensis occurs in the Serra do Cabral mountain range in Buenopolis municipatility, Minas Gerais, Brazil. Despite its diminutive size, it has arched yellowish-green leaves and pinnae not as narrow as the species of the grass-like Butia. The new species is closely related to B. archeri, based on morphology, phenology (flowering time) and habitat. They differ in leaf anatomy, plant size, color and size of inflorescence. Some novelties in Butia flower morphology, such as striated cuticle of anthers, functional staminodes presenting evidence of secretory activity, raphides on the petals of pistillate flowers and the cappilinection adhesion of petal margins, were introduced here and suggested as a new approach for future taxonomical and evolutionary studies of this genus. The isolated and small groups of fibers in the mesophyll and a non-vascular fiber bundle connected to the adaxial epidermis in the leaf midrib have not been found in any other Butia so far. The one population recorded for the new species is restricted to an area near the limits of Serra do Cabral State Park, clearly vulnerable to different forms of anthropic pressure. So, it is strongly recommended an extension in area of Serra do Cabral State Park to include the B. buenopolensis range of occurrence within its borders.