American Society of Hirudotherapy

Celebrity with a neglected taxonomy: molecular systematics of the medicinal leech (genus Hirudo)

Phylogenetics article published in Molecular Phylogenetics and Evolution (2004)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Preclinical (animal)Genomics & ProteomicsTrontelj P, Utevsky SY · Molecular phylogenetics and evolution, 2004

Abstract

The medicinal leech is the most famous representative of the Hirudinea. It is one of few invertebrates widely used in medicine and as a scientific model object. It has recently been given considerable conservation effort. Despite all attention there is confusion regarding the taxonomic status of different morphological forms, with many different species described in the past, but only two generally accepted at present. The results of the phylogenetic analysis of a nuclear (ITS2+5.8S rRNA) and two mitochondrial gene sequences (12S rRNA, COI) suggest that the genus Hirudo is monophyletic. It consists, apart form the type Hirudo medicinalis and the East Asian Hirudo nipponia, of three other, neglected species. All of them have already been described either as species or morphological variety, and can readily be identified by their coloration pattern. The type species is in weakly supported sister relation with Hirudo sp. n. (described as variety orientalis) from Transcaucasia and Iran. Sister to them stands Hirudo verbana from southeastern Europe and Turkey, which is nowadays predominantly bred in leech farms and used as 'medicinal leech.' The North African Hirudo troctina is the sister taxon to this group of Western Eurasian species, whereas the basal split is between H. nipponia and the Western Palaearctic clade.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal ArticleResearch Support, Non-U.S. Gov't
Indexed MeSH termsAnimalsBayes TheoremCell NucleusHirudo medicinalisLikelihood FunctionsMitochondriaPhylogenyRNA, Ribosomal

Summary

Molecular phylogenetic analysis (ITS2+5.8S rRNA, 12S rRNA, COI) demonstrates Hirudo genus monophyly and three previously neglected species (H. verbana, H. orientalis, H. troctina) alongside H. medicinalis and H. nipponia.

Why This Matters for Hirudotherapy

This phylogenetic study examined the molecular systematics of the genus Hirudo using nuclear (ITS2 + 5.8S rRNA) and mitochondrial (12S rRNA, COI) gene sequences, finding the genus monophyletic and comprising at least five species including H. medicinalis, H. verbana, H. nipponia, H. troctina, and a variety orientalis from Transcaucasia and Iran. The authors note that H. verbana from southeastern Europe and Turkey is nowadays predominantly bred in leech farms and used as the 'medicinal leech,' despite the type species being H. medicinalis. This is indirectly relevant to ASH as it clarifies species-level taxonomy critical for standardizing and identifying which Hirudo species are actually used therapeutically. The caveat is that this is purely systematic/taxonomic research with no clinical or therapeutic data.

Citation

Celebrity with a neglected taxonomy: molecular systematics of the medicinal leech (genus Hirudo).

Trontelj P, Utevsky SY · Molecular phylogenetics and evolution, 2004

DOI

Added to ASH library: May 26, 2026 · Site last updated: June 18, 2026

This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.