Iris luojiensis, sp. nov. from Southwest China is described and illustrated. This species occurs on shrub slopes in mountainous regions of southwest China. Iris luojiensis is morphologically similar to Iris japonica Thunb., Iris calcicola Z.C.Lu, Z.P.Huang & Yan Liu and Iris watii Baker, but easily distinguished from them by its bluish-violet flowers, 3-6 flowering-stem branches, leaf size, particularly the upper leaves, and by only having two to three (seldom one) flowers per bract. A phylogenetic analysis based on the complete plastid genome supports the separation of I. luojiensis from other morphologically related species. According to morphological and molecular evidence, I. luojiensis can be placed in the I. sect. Lophiris.

Phylogenetic analysis of chloroplast genomes: CTAB (Cetyl Trimethyl Ammonium Bromide) method (Doyle and Doyle, 1987). The total extracted DNA was sent to Wuhan BGI for further database construction and sequencing. A 300-400 bp DNA small fragment library was constructed using the BGISEQ-500 platform. Subsequently, paired-end 150 (PE150) sequencing was performed using the MGISEQ-2000 platform, resulting in 2G paired-end data in fastq format.