The complete mitochondrial genome of (Clitellata: Glossiphoniidae).

We present the complete mitochondrial genome sequence of a recently described new leech species named Yang & Bolotov 2021 collected in central China. The mitochondrial genome is 14,984 bp in length and consists of 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes, all of which are encoded on a single strand. It exhibited a strong A + T bias of 72.

Expression patterns of kiss2 and gpr54-2 in Monopterus albus suggest these genes may play a role in sex reversal in fish.

Due to its exceptionally small genome size and protogynous hermaphroditism, Monopterus albus has been proposed as a model for vertebrate sexual development. The Kiss/GPR54 system is a central regulator of sexual development in most vertebrates, but its role in sex reversal remains hypothetical. In contrast to mammals, fishes often possess more than one copy of the kiss and gpr54 genes.