A new genus and species of cave-dwelling leech from China in the family Salifidae: taxonomy, phylogeny, and mitochondrial genome characterization

Accurate identification of leech species is critical for biodiversity conservation and evolutionary studies. However, due to the ambiguity and variability of some key characteristics, Salifidae remains a rather poorly known group of Erpobdelliformes. In this study, a new genus of salifid leech, Troglobdella gen. nov., is established, and a new species, Troglobdella guizhouensis sp. nov., is described based on specimens collected from a cave in Guizhou Province, Southwest China.

Phylogenetic analyses based on mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 18 S rRNA gene sequences reveal that Troglobdella guizhouensis represents a distinct lineage within a clade that also includes the troglobiotic species Shibabdella wulingensis Tang & Liu, 2025, and the terrestrial Odontobdella gaowangjiensis Yin & Liu, 2025, both of which are known from Hunan Province. This suggests that cave-related morphologies in Chinese salifid leeches may have evolved independently.

The complete mitochondrial genome of the new species was assembled into a circular molecule of 15,732 bp, comprising 13 protein-coding genes, 22 tRNAs, and 2 rRNAs. This study contributes new insights into the taxonomy, systematics, and mitochondrial architecture of cave-adapted leeches.