A new species of medicinal leech in the genus Linnaeus, 1758 (Hirudiniformes, Hirudinidae) from Tianjin City, China.

Medicinal leeches in the genus have been utilized for therapeutic procedures for thousands of years. To date, six known species of are widely distributed in different regions of the Eurasian continent. In this study, a new medicinal leech species Liu, is described based upon specimens collected from Tianjin City, China. The new species can be distinguished from its congeners by a combination of characters: blackish green dorsum with five continuous yellow longitudinal stripes; six sensillae on dorsal annulus a2 of segments VIII-XXV; greyish green ventrum with irregular bilateral dark brown spots; dorsum and abdomen separated by a pair of pale yellow stripes; front half atrium wrapped by white prostate; apparent albumen gland; epididymis massive in relation to ejaculatory bulb. The phylogenetic tree based upon COI implies a sister relationship to Whitman, 1886. A key to the known species is provided.