Six new species of Milla (Asparagaceae: Brodiaeoideae) from Mexico

Background and Aims: Milla, with ten species, is the most diverse genus of a monophyletic group of geophytic herbs named Milla clade (Brodiaeoideae: Asparagaceae). Milla is differentiated from related genera by its white aromatic hypocrateriform flowers, and the flower tube and gynophore longer than the tepals. Milla biflora has traditionally been understood as a species of wide geographic distribution. However, recent studies have shown that various populations are different entities based on anatomy, morphology and genetics, and should be recognized as new species. The aim of this study is to describe and illustrate six new species of Milla, whose populations were considered part of Milla biflora. Methods: Botanical specimens were collected in the distribution area of Milla throughout the Mexican Republic, between 2012 and 2015. Individuals from the visited populations were subjected to morphological, anatomical and phylogenetic analyses. In addition, specimens from fifteen herbaria were revised, which allowed evaluating vegetative and reproductive characters. Key results: Six species of Milla are described and illustrated, differentiated morphologically from M. biflora by the number of leaves, trans- verse-sectional shape of the leaf, size of the scape, number of flowers, color, and size of the tepals as well as the number of tepal veins. Conclusions: Milla is a natural group of geophytic herbs that have diversified throughout the Mexican Republic. The new species described here reveal that Milla has received little attention in its biological diversity.

Automated summary

This study describes and illustrates six new species of Milla, highlighting the diversity of Milla's distribution in the Mexican Republic. Milla's biological diversity has been relatively understudied.