The European medicinal leech is one of vanishingly few animal species with direct application in modern medicine. In addition to the therapeutic potential held by many protease inhibitors purified from leech saliva, and notwithstanding the historical association with quackery,Hirudo medicinalishas been approved by the United States Food and Drug Administration as a prescription medical device. Accurate annotation of bioactive compounds relies on precise species determination. Interpretations of developmental and neurophysiological characteristics also presuppose uniformity within a model species used in laboratory settings. Here, we show, with mitochondrial sequences and nuclear microsatellites, that there are at least three species of European medicinal leech, and that leeches marketed asH. medicinalisare actuallyHirudo verbana. Beyond the obvious need for reconsideration of decades of biomedical research on this widely used model organism, these findings impact regulatory statutes and raise concerns for the conservation status of European medicinal leeches.

Erpobdellid leeches of the genus Trocheta are among the biggest and most charismatic members of their class. The studies of the group have a long and complicated history due to the lack of reliable distinguishing features, which impedes the taxonomy of the genus. A number of Trocheta species have been misclassified for years if not centuries. Our present research demonstrates that the genus Trocheta is characterized by high cryptic diversity since some populations that have been viewed as the same species should be, in fact, assigned to different species. Trocheta leeches from the Dniester basin and the Crimean Peninsula have been both confused with each other and erroneously assigned to species that do not occur in southern Ukraine. Here, a new species from the Crimean Peninsula, Trocheta blanchardi sp. nov., is described based on a phylogenetic analysis of cox1 gene sequences and a reassessment of morphological characters such as colouration, annulation, size and arrangement of papillae, and genital anatomy. The analysis suggests close relationships of T. blanchardi sp. nov. to Anatolian species. Given its fragile habitats and restricted range, the species needs serious protection and further surveys. Obviously, more species await description as is evident from the significant genetic differences between leech populations. http://zoobank.org/urn:lsid:zoobank.org:pub:8610460D-862B-4F28-8520-5C8D11AEB015

Acanthobdellida gnaw into the sides of salmonid fishes in frigid Arctic lakes and rivers, latching on with fearsome facial hooks. Sister to leeches, they are an ancient lineage with two described species. Unfortunately, Acanthobdellida are rarely collected, leading to a paucity of literature despite their unique morphology. Populations range from Eurasia to Alaska (USA), but few specimens of Acanthobdella peledina are represented in molecular studies, and no molecular data exist for Paracanthobdella livanowi, making their taxonomic position difficult to assess. We use phylogenetics and morphology to determine whether allopatric populations of A. peledina are distinct species and assess the current classification scheme used for Acanthobdellida. We produce a new suborder, Acanthobdelliformes, to match the taxonomy within Hirudinea. Scanning electron micrographs indicate species-level differences in the anterior sucker and facial hooks; molecular phylogenetics mirrors this divergence between species. We assign both species to the family Acanthobdellidae and abandon the family Paracanthobdellidae. Alaskan and European A. peledina populations are morphologically similar, but appear phylogenetically divergent. Our data strongly suggest that members of the order Acanthobdellida diverged relatively recently in their ancient history, but based on genetic distance, this divergence appears to pre-date the most recent cycles of glaciation.

Phylum Annelida are ubiquitous metazoans found in almost every terrestrial and aquatic habitat on Earth. Historically, taxonomic studies on the phylum have been focused largely on its majorgroups, polychaetes, oligochaetes and leeches, so that while family-level keys for each group are available, no single-source identification guide exists to the world’s annelid families. Here, the first illustrated linear key to annelid families is provided and family-level descriptions and diagnoses that distinguish individuals of each family from those of other families in the phylum are updated. This information is generated from an annelid DELTA database of 334 characters and 166 mostly family-level taxa. A link is provided to downloadable software (ANNiKEY Interactive) allowing the same data to be interrogated using the open-source DELTA program Intkey, which enables both interactive identification and taxonomic query functionality. For each family-level taxon, a diagnosis, full description, links to taxonomic data at the World Register of Marine Species, illustrations of diagnostic features, and a summary of the recent literature, including a list of published keys to genera and species are provided.