Atacamallium, a new genus in Amaryllidaceae-Allioideae-Leucocoryneae, is introduced with a description of its type Atacamallium minutiflorum, endemic to the coastal Atacama Desert of northern Chile. Phylogenetic analyses of DNA sequences, along with morphological characters and its distribution pattern, support the new genus and place it as a putative sister to Leucocoryne, which is readily distinguished from Atacamallium by its floral morphology. Atacamallium minutiflorum differs from other species of Leucocoryneae by its overall smaller flowers, tepals fused only at the base, six stamens in a single series, and trifid stigma. A morphological description, a distribution map, an illustration, and the assessment of the conservation status of the new species, besides an updated key to the genera of Leucocoryneae, are provided. Additional data from multiple single-copy nuclear genes are needed to clarify the relationships within the tribe.

Keywords: Alliaceae, Atacama, Leucocoryneae, phylogeny, taxonomy