Abstract
Although the European medicinal leech (Hirudo medicinalis L. 1758) is one of the best-known members of the Hirudinea due to its use in phlebotomy, this species has been confused with the Mediterranean taxon H. verbana Carena 1820. Here we describe the morphology of adult and juvenile H. medicinalis and document its genetic distance to H. verbana, using newly acquired mitochondrial DNA-sequence (cytochrome c oxidase subunit I, CO-I)-data from specimens collected in Germany. Our CO-I analysis shows that H. medicinalis and H. verbana differ by 9.4 %. Hence, the original Hirudo-population diverged ca. 10 million years ago so that today two geographically separated biospecies exist that co-occur in only a few natural habitats. We analyzed the behaviour of adult H. medicinalis, but could not find differences with respect to its sister taxon H. verbana. Finally, we summarize the occurrence of H. medicinalis in Central Europe and conclude that this once widely distributed freshwater species largely disappeared in many countries. We suggest that the loss of natural freshwater ecosystems, with flat, warm banks, and amphibians (frogs, newts and toads) as preferred host organisms for the juveniles, are largely responsible for the decline of H. medicinalis in Northern Europe.
Highlights
Among the currently ca. 14 000 accepted species of Annelida found worldwide in freshwater, marine and terrestrial ecosystems, Linnaeus (1758) first described the two most well-known forms: the earthworm (Lumbricus terrestris) and the medicinal leech (Hirudo medicinalis)
We describe the morphology of juvenile and adult H. medicinalis-individuals, add information on its evolutionary distance to its sister taxon H. verbana, and summarize observations on the behaviour, ecology and distribution of this endangered species
Based on c oxidase subunit I (CO-I)-sequences acquired in our laboratory for H. verbana and other leech species (Kutschera 2010, 2011; Kutschera et al 2007, 2013), supplemented by additional GenBank CO-I-data, the results shown in Table 1 were obtained
Summary
Among the currently ca. 14 000 accepted species of Annelida (segmented worms) found worldwide in freshwater, marine and terrestrial ecosystems, Linnaeus (1758) first described the two most well-known forms: the earthworm (Lumbricus terrestris) and the medicinal leech (Hirudo medicinalis). 14 000 accepted species of Annelida (segmented worms) found worldwide in freshwater, marine and terrestrial ecosystems, Linnaeus (1758) first described the two most well-known forms: the earthworm (Lumbricus terrestris) and the medicinal leech (Hirudo medicinalis). This Linnaean system of the “classis Vermes”, with the three orders “Intestina, Mollusca and Testacea”, was soon replaced by Lamarck’s more detailed account of classification of the “lower animals” (Vinarski 2014). Based on detailed analyses of pigment patterns and DNA-sequen ces, it was documented that H. officinalis is not a “colour variant of Linnaeus’ type species”, but a separate taxon, the Mediterranean medicinal leech H. verbana Carena, 1820
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