Recently, the chloroplast genome of Viola verecunda from a sample collected in Japan has been published. Although the name is often recognized as a taxonomic synonym of Viola arcuata , the genetic identity of the two species has never been compared intensively. We report the complete chloroplast genome sequence of V. arcuata, of which sample was collected from Seoul, Korea. The cp genome of V. arcuata (OM301625) has 157,870 bp in length and is composed of four regions: 86,366 bp of a large single-copy (LSC) region, 17,298 bp of a small single-copy (SSC) region, and 27,103 bp of a pair of inverted repeats (IRs). The complete genome contains 130 genes, including 84 protein-coding genes, eight rRNA genes, and 37 tRNA genes. When comparing chloroplast genomes between V. verecunda , and V. arcuata , 34 different loci were recognized: 12 SNPs and 22 indels. In the coding regions, there were two amino acid insertions ( ndhI ) caused by one base deletion, three synonymous substitutions ( ndhF, ccsA, and ndhI ), and six nonsynonymous substitutions ( matK , rpoC2 , ndhF , ycf1 , and two rpl2 s on each IR region). In non-coding regions, variants of 19 polyN sites, one microsatellite, two insertions, and two SNPs were recognized. Phylogenetic analysis confirms a sister or nearly identical relationship between two genomes. This study will provide the genetic basis for solving a taxonomic problem between V. arcuata and V. verecunda .

The VIOLA ALBIDA complex is a complicated group with taxonomic problems having continuous leaf variations and composed of taxa related to the following names: Viola albida , V. albida var. takahashii , and V. chaerophylloides. As a first step to understanding the genomic nature of this complex, this study identified the whole chloroplast genome of V. albida . The genome is 157,692 bp in length (36.3% of GC content) and contains four subregions: a large single copy region of 86,220 bp, a small single copy region of 17,248 bp, and a pair of inverted regions of 27,112 bp each. An annotation of the gene identifies 111 unique genes, including 77 protein-coding genes, four rRNA genes, and 30 tRNA genes. The phylogenetic analysis of this genome with selected cp genomes from Viola identifies the close relationship between V. albida and V. ulleungdoensis. It is noteworthy that V. chaerophylloides , traditionally recognized as a member of the VIOLA ALBIDA complex, is genetically distant from V. albida and forms a sister group of all other members of the subsection Patellares . Our genome report is expected to serve as a basis for understanding the identity of the VIOLA ALBIDA complex.