Complete chloroplast genome and phylogenetic analysis of Richardia brasiliensis (Rubiaceae, Rubioideae, Spermacoceae)

We determined the chloroplast genome of Richardia brasiliensis. The genome was 154,573 bp with a typical quadripartite structure: a large single-copy region (84,388 bp), a small single-copy region (17,411 bp), and two inverted repeat regions (26,387 bp each). It contained 128 genes: 83 protein-coding genes (PCGs), 37 transfer RNA, and eight ribosomal RNA genes. For phylogenetic inference, 77 shared PCGs were concatenated from the chloroplast genomes of 52 taxa, revealing that R. brasiliensis is the most closely related to Oldenlandia corymbosa. This chloroplast genome provides a valuable resource for Spermacoceae and facilitates future studies to resolve intergeneric relationships.