Abstract
Symbiochlorum hainanensis Gong et al. (2018). is a unicellular green alga belonging to Ulvophyceae, Chlorophyta, and considered as an important species in coral-algae symbiont areas. In this study, we revealed firstly the mitochondrial genome sequence of the S. hainanensis. This mitochondrial genome was a circular DNA molecule of 59,508 bp, including 24 transfer RNA genes, 3 ribosomal RNA genes, and 31 protein-coding genes. The GC content of the genome was 35.4%. The phylogenetic tree suggested that S. hainandiae was a sister to the OUU clade within the class Ulvophyceae. The mitochondrial genome structure and gene content of S. hainanensis supported that S. hainanensis was a new unidentified green alga in Ulvophyceae.