Complete Mitochondrial Genome Sequencing of the Calanoid Copepod Bestiolina similis (Sewell, 1914) from the Chennai Coast

Abstract

Copepods are the most abundant metazoans on Earth, exhibit remarkable species diversity and global distribution. Accurate species identification of copepods presents a challenge due to their cryptic nature, necessitating meticulous examination and differentiation. To address this challenge, innovative approaches utilizing molecular markers have emerged, enabling more reliable and precise species identification. Mitochondrial genes, which are characterized by high variability, have proven invaluable in uncovering taxonomically significant variations among copepod species. In this study, we present the first complete mitochondrial genome analysis of the marine calanoid copepod Bestiolina similis (Sewell, 1914). Recent investigations employing whole mitochondrial genome-based phylogenetic analyses have generated considerable interest in exploring the deep branching patterns of arthropods. The complete mitochondrial genome of B. similis spans 23,704 base pairs and includes 13 protein-coding genes and 20 transfer RNA genes. The nucleotide composition of the mitochondrial genome is characterized by 43.42% adenine, 43.22% thymine, 6.48% guanine, and 6.88% cytosine. Maximum likelihood-based phylogenetic analysis of the mitochondrial genome were constructed of the available copepod species. Mitochondrial ge-nome-based phylogenies often reveal intriguing and distinctive topologies compared to traditional phylogenetic approaches. However, the sequencing of copepod mitochondrial genomes, particularly within the calanoid copepods remains limited. Therefore, this study aims to construct a phylogenetic tree based on the extracted mitochondrial genome, incorporating available data, to enhance our understanding of the evolutionary relationships among calanoid copepods.