Complete chloroplast genome and phylogenetic analysis of <i>Richardia brasiliensis</i> (Rubiaceae, Rubioideae, Spermacoceae)

We determined the chloroplast genome of <i>Richardia brasiliensis</i>. 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 <i>R. brasiliensis</i> is the most closely related to <i>Oldenlandia corymbosa</i>. This chloroplast genome provides a valuable resource for Spermacoceae and facilitates future studies to resolve intergeneric relationships.