Arhynchobdellida, the proboscisless leeches, are a monophyletic order of leeches. They are defined by the lack of the protrusible proboscis that defines their sister taxon, the Rhynchobdellida.^[1][2][3] Arhynchobdellida is a diverse order, compromising both aquatic and terrestrial, besides sanguivorous and predatory, leeches.^[3] The order is divided into two suborders, Erpobdelliformes and Hirudiniformes (sometimes also called the Pharyngobdelliformes and Gnathobdelliformes, respectively).^[1]

Quick Facts Proboscisless leeches, Scientific classification ...

Proboscisless leeches
A giant Americobdella species from southern Chile.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Annelida
Clade:	Pleistoannelida
Clade:	Sedentaria
Class:	Clitellata
Subclass:	Hirudinea
Infraclass:	Euhirudinea
Order:	Arhynchobdellida Blanchard, 1894
Suborders
Erpobdelliformes Hirudiniformes and see text
Synonyms
Arhynchobdellae Stuart, 1982[verification needed] Pharyngobdellae Pharyngobdellida Johnson, 1913

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Historically, the Arhynchobdellida were split into two orders, the Gnathobdellida and the Pharyngobdellida.^[4] The Gnathobdellida were jawed and carnivorous or parasitic while the Pharyngobdellida were jawless and carnivorous.^[5][6] Current taxonomy accepts the order Arhynchobdellida and divides into two suborders. There are 215 species of Arhynchobdellid leech, in 47 genera and 13 families.^[7] The placement of Americobdellidae is uncertain; it has rudimentary jaws and is terrestrial.

Erpobdelliformes

Erpobdelliformes are jawless predators of aquatic invertebrates of varying sizes, including insect larvae, mollusks, and other annelids.^[8][9] Unlike other leeches, they do not penetrate the skin of hosts; and are not at all parasitic.^[10][11] The pharynx is spirally twisted and very large to allow for large prey; it can constitute up to one third of the leech's body length.^[1]