Taxonomy and Melanism Patterns of Freshwater Leeches in the Genus Glossiphonia (Hirudinea: Glossiphoniidae) from Northeast Asia

Freshwater leeches belonging to the genus Glossiphonia Johnson, 1816 are fairly common benthic annelids in freshwater ecosystems throughout Eurasia, but the taxonomy of this group remains poorly resolved, and the species content of some local faunas is unsatisfactorily known. For example, it was thought that the only widespread species, Glossiphonia complanata (Linnaeus, 1758), dwells in Northeast Asia. Here, we revise the Northeast Asian Glossiphonia leeches with an integrative taxonomic approach. This revision is based on the largest DNA-sequence and morphological datasets collected to date. Two Glossiphonia species are recorded from the region. First, Glossiphonia koreaensis sp. nov., a putative regional endemic species, was discovered in South Korea. Second, a valid name and complete description are provided for Glossiphonia mollissima Moore, 1898 (non-Grube, 1871). The latter name was wrongly applied through misidentification and, according to ICZN (Article 49), is unavailable. Hence, we propose a new name, Glossiphonia moorei sp. nov., in memory of Dr. J. Percy Moore, who discovered this leech. It is a prospective trans-Beringian species, ranging through Eastern Siberia, the Russian Far East, and Alaska (although Alaskan records are based on nonsequenced samples), showing a significant proportion of melanic individuals in samples north of the Arctic Circle. The latter pattern may reflect substrate-induced cryptic coloration (camouflage), but this hypothesis needs to be statistically checked in the future. Finally, a complete checklist of Glossiphonia species is presented.