DNA was extracted from silica-dried leaf samples of 20 individuals ofL. columnaris using a modified cetyltrimethylammonium bromide (CTAB) protocol (Doyle & Doyle 1987). Library construction, sequence generation, and bioinformatics processing were done at the Indiana University Center for Genomics and Bioinformatics. Sequence generation was performed using Illumina NextSeq and Illumina MiSeq platforms. Additionally, we downloaded 22 plastome sequences of 22 taxa of Campanulaceae from TreeBASE no. S15797 (Knox 2014) and GenBank accessions (Knox & Li 2017).

A total of 20 individual plastid genomes of L. columnaris were newly sequenced and assembled. Eleven plastomes represent populations from three sky islands in Bioko (Equatorial Guinea), and nine plastid genomes are from two sky islands in Cameroon (Figure 1). Moreover, the phylogenetic tree included two more plastome sequences of L. columnaris from South Bioko (Perez Perez 3103, MF061188) and another from Mt. Cameroon (Muasya 2085, MF061187) obtained from GenBank (Knox & Li 2017) .