Axinaea filandiensis (Melastomataceae, Merianieae), a new species from Colombia, and comments on the circumscription of Axinaea and groups in Meriania

Background and Aims: Axinaea is a predominantly Andean genus, with one species found in the mountains of Costa Rica and Panama. It is similar to Meriania, and the only feature that separates them from each other is the shape of the dorsal connective of the anther. The discovery of a new species, described here, with anther connective characters intermediate between the two genera, raised the need to improve the circumscription of Axinaea and document variation within Meriania, aspects that are addressed in this paper.Methods: A new species of Axinaea is described from collections deposited in the UDBC herbarium of the Distrital University of Bogotá. The degree of threat is evaluated and the need for conserving the species is described. In addition, various groups within Meriania, including Axinaea, are summarized, and a unique set of characters for Axinaea is proposed.Key results: Axinaea filandiensis sp. nov. is characterized by its 4-merous flowers, isomorphous stamens with blue anthers and globose-ellipsoid dorsal connectives. It is known only from the type locality and its conservation status is proposed as Critically Endangered (CR). Seven groups are described in Meriania, including Axinaea, and a unique set of characters is proposed for the latter genus, considering non-nectariferous flowers, cucullate corolla, isomorphic or slightly dimorphic stamens, anthers with the vascular bundle of the connective tissue directed backwards, and inappendiculate and globose to globose-elliptic connective. According to this circumscription, one species described in Meriania (M. rubrifolia) establishes its position within Axinaea.Conclusions: Axinaea filandiensis represents a critically endangered species that requires urgent conservation action. The unique set of characters established in this paper clarifies the separation between Axinaea and Meriania. It is proposed to maintain both genera separate, considering that Meriania is an artificial group that should be split into several genera.