Characterization of the Complete Mitochondrial Genome of Agelas nakamurai from the South China Sea

The genus sponges are widely distributed and provide shelter for organisms that inhabit reefs. However, there is a lack of research on the genetic diversity of the sponges. Additionally, only one mitochondrial genome has been documented, leaving the characteristics of the genus's mitogenome in need of further clarification. To address this research gap, we utilized Illumina HiSeq4000 sequencing and de novo assembly to ascertain the complete mitochondrial genome of sp. specimens, sourced from the South China Sea. Our analysis of the barcoding similarity and phylogenetic relationship reveals that taxonomically, the sp. corresponds to . The mitogenome of is 20,885 bp in length, encoding 14 protein-coding genes, 24 transfer RNA genes, and 2 ribosomal RNA genes. Through a comparison of the mitochondrial genes, we discovered that both and have an identical gene arrangement. Furthermore, we observed a deletion in the gene and duplication and remodeling of the gene in the 's mitogenome. Our evolutionary analysis also identified lineage-specific positive selection sites in the and genes of the sponges' mitogenome. These findings shed light on the gene rearrangement events and positive selection sites in the mitogenome of , providing valuable molecular insights into the evolutionary processes of this genus.