First Mitogenome of Endangered Enteromius thysi (Actinopterygii: Cypriniformes: Cyprinidae) from Africa: Characterization and Phylogeny

The complete mitochondrial genome of endangered Enteromius thysi was determined from Cameroon in Western Africa. The genome was 16,688 bp in length, comprising 37 genes (13 PCGs, 2 rRNAs, 22 tRNAs, and an AT-rich control region). The heavy strand accommodates 28 genes (12 PCGs, 2 rRNAs, and 14 tRNAs), whereas the light strand holds 9 genes (NAD6 and 8 tRNAs). The E. thysi mitogenome is AT-biased (60.5%), as exhibited in other Enteromius species. Most of the PCGs start with the ATG initiation codon, except COI, with GTG, and seven PCGs end with the TAA termination codon, except some with an incomplete termination codon. Most of the tRNAs showed classical cloverleaf secondary structures, except tRNA-serine (trnS1). Bayesian phylogeny distinctly separated E. thysi from other congeners. The control regions of Enteromius species exhibited highly variable nucleotides, and parsimony-informative sites were found in the conserved sequence block-III (CSB-III) compared with other domains and a unique 9 bp tandem repeat (ATGCATGGT) in the variable-number tandem repeats (VNTRs) region of E. thysi. The present phylogeny with limited mitogenomes showed an uneven diversity and evolutionary patterns of Enteromius species distributed in the northwestern and southeastern riverine systems in Africa, which warrants further investigation. Based on the results of the present study, we recommend additional surveys, in-depth taxonomy, and the generation of more mitogenomes that could resolve the diversification pattern of Enteromius species in Africa.