Iris longnanensis Z.F.Bai, Y.E.Xiao, F.Y.Yu (Iridaceae: Iris subg. Iris sect. Pseudoregelia), a novel herbaceous species native to the arid and thermal valleys of Longnan city, Gansu Province, China, is described and illustrated here. Morphologically akin to I. leptophylla Lingelsheim, I. longnanensis is distinguished by its dense, persistent foliage and notably short new leaves (6.6–15.1 cm) during the blooming season, along with its distinctive purplish-brown flowering stem. Phylogenetic analyses based on chloroplast DNA sequences corroborate the classification of I. longnanensis within the section Pseudoregelia, highlighting the significance of this new species discovery for understanding the evolution and diversity within the genus.

Keywords: Longnan, plastid DNA, Iris longnanensis, section Pseudoregelia