Characterization and phylogenetic analysis of the complete chloroplast genome of the rare endemic Isodon rivularis (Lamiaceae) from the Western Ghats

Isodon rivularis (Wight ex Hook.f.) H.Hara is a perennial herb endemic to the Western Ghats. In this study, we sequenced and assembled its complete chloroplast genome, which is 152,286 bp in length. The plastome exhibits a typical quadripartite structure, comprising a large single-copy region (LSC) of 83,159 bp, a small single-copy region (SSC) of 17,671 bp, and a pair of inverted repeats (IRs) regions of 25,728 bp each. The overall GC content of the genome is approximately 37.6%. A total of 114 genes were identified, including 80 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The two copies of the ycf15 gene, both containing an internal stop codon, and the rpoC2 gene, which includes a frameshift mutation, were identified as pseudogenes. Bayesian phylogenetic analysis placed I. rivularis within Clade I, where it forms a sister lineage to all other species in the clade.