The first complete chloroplast genome of <i>Cymodocea rotundata</i> Asch. &amp; Schweinf. 1870 (Cymodoceaceae), an Indo-Pacific seagrass

<i>Cymodocea rotundata</i> Asch. & Schweinf. 1870 (Cymodoceaceae) is a seagrass found in the tropical and temperate Indo-Pacific coastal waters. Seagrass beds composed of <i>C. rotundata</i> and other seagrasses form ecologically valuable ecosystems. In this study, the complete chloroplast genome of <i>C. rotundata</i> was sequenced and characterized for the first time. It is a circular genome of 158,311 bp in length, consisting of a large single-copy region (88,451 bp), a small single-copy region (18,836 bp), and a pair of inverted repeats (25,512 bp). A total of 130 genes were annotated, including 86 protein-coding genes (PCGs), 36 transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. Seven PCGs and 6 tRNA genes contain 1 intron, and 3 PCGs contain 2 introns. In addition, 7 PCGs, 7 tRNA genes, and all the rRNA genes are multi-copy genes with 2 copies. Phylogenetic analysis shows that <i>C. rotundata</i> clusters with <i>Syringodium isoetifolium</i> in one clade, both belonging to the family Cymodoceaceae. This study provides new information to support further research on the phylogeny of Cymodoceaceae.