Characterisation and phylogenetic analysis of the complete mitochondrial genome of two endemic lampreys from Greece (Caspiomyzon hellenicus and Caspiomyzon graecus) using Long-Read technology.

BACKGROUND

The genus Caspiomyzon is comprised of three species, two of which are found in Greece (Caspiomyzon hellenicus and Caspiomyzon graecus). Both species are endemic with very restricted distribution and are classified as Critically Endangered. Caspiomyzon hellenicus is restricted to Tenagi, Philippi and C. graecus to Louros River. No studies have characterized their mitochondrial genomes.

METHODS AND RESULTS

The complete mitochondrial genome of C. hellenicus and C. graecus was generated with Oxford Nanopore long-read technology, and it was processed using various bioinformatics approaches. The final assembled contig length was 16,763 bp and 17,123 bp, respectively, and composed of 13 protein-coding genes, two ribosomal RNA genes, 22 tRNA genes, and two control regions. Repetitive sequences were detected between and within the control regions. The overall GC composition was approximately 36% for both species. The results of phylogenetics analysis using Bayesian inference and Maximum likelihood methods revealed that the Geotria australis species was sister to northern hemisphere lampreys, whereas Mordacia species constitutes a monophyletic group. Divergence time between the Greek Caspiomyzon species took place at approximately 0.7 Mya.

CONCLUSIONS

This study enhanced our understanding of the taxonomic and phylogenetic relationships within the Caspiomyzon genus from Greece based on the characterization of the full mitochondrial genomes from long-reads technology. Such efforts can aid their conservation and management locally.