| Medicinal leech, Hirudo verbana, Hirudinidae, Arhynchobdellida, Haemopis sanguisuga|
Hirudo is a genus of leeches of the family Hirudinidae. It was described by Linnaeus in 1758.
There are two well-accepted species within the genus:Hirudo medicinalis Linnaeus, 1758
Hirudo nipponia Whitman, 1886
Three other species, previously synonymized with Hirudo medicinalis, were described in 2005 and are gaining acceptance:Hirudo verbana
Species are typically exterior feeders. They have jaws that typically consist of approximately 60 teeth and do not possess papillae.
Hirudo medicinalis: Britain and southern Norway to the southern Urals, probably as far as the Altai Mountains (the deciduous arboreal zone)
Hirudo verbana: Switzerland and Italy to Turkey and Uzbekistan (the Mediterranean and sub-boreal steppe zone)
Hirudo orientalis: Transcaucasian countries, Iran, and Central Asia (mountainous areas in the sub-boreal eremial zone)
Hirudo sulukii: Kara Lake of Adiyaman, Sülüklü Lake of Gaziantep and Segirkan wetland of Batman in Turkey
Hirudo troctina: North-western Africa and Spain (Mediterranean zone)
Hirudo nipponia: East Asia, including Far East district in Russian, Japan, Korea, China, Mongolia, Ryukyu Islands and Taiwan
H. verbana is further divided into non-overlapping Eastern and Western phylogroups.
While H. medicinalis has long been used in hirudotherapy, and is approved by the US FDA as a prescription medical device, a 2007 study employing genetic analysis found that the species being marketed as H. medicinalis, possibly for decades, was the recently distinguished H. verbana.
A 2010 study of data gathered four species proposed an IUCN status of Near Threatened for H. medicinal is, H. verbana, and H. orientalis, and a status of Data Deficient for Hirudo troctina.