Americobdella is a genus of carnivorous leech

Leech

Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Like other oligochaetes such as earthworms, leeches share a clitellum and are hermaphrodites. Nevertheless, they differ from other oligochaetes in significant ways...

es from southern Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, comprising only the species Americobdella valdiviana.

Taxonomy

Philippi, who originally classified A. valdiviana as an erpobdellid leech, noted that Americobdella valdiviana was similar to Trocheta "in both appearance and habit". It is phylogenically between two major groups of leeches, the Rhynchobdellida

Rhynchobdellida

Rhynchobdellida, the jawless leeches, are classified as an order of the Hirudinea. But leech taxonomy and systematics will eventually be revised in due time, not because there are many uncertainties about their phylogeny, but because the major clades of clitellate annelids – and whether the...

 and the Arhynchobdellida

Arhynchobdellida

The proboscisless leeches, Arhynchobdellida, are classified as an order of the Hirudinea. But leech taxonomy and systematics will eventually be revised in due time, not because there are many uncertainties about their phylogeny, but because the major clades of clitellate annelids - and whether the...

. Recent work has suggested A. valdiviana is more closely related to the Erpobdelliformes than the Hirudiniformes

Hirudiniformes

The Hirudiniformes are one of the currently-accepted suborders of the proboscisless leeches . Their most well-known member is the European Medical Leech, Hirudo medicinalis, and indeed most of the blood-sucking "worms" as which leeches are generally perceived belong to this group...

.

Description

Americobdella valdiviana is a predator and has only rudimentary jaws. Because of these features, it was originally classified as an erpobdellid

Erpobdellidae

Erpobdellidae is a family of leeches. They have three or four pairs of eyes, but never have true jaws, and are typically long. Most are scavengers on small invertebrates, which they often swallow whole....

leech. A. valdiviana is grey-coloured on the dorsal side with a yellowish ventral side. Whether eyes are present in this species is a matter of debate. While Philippi originally described Americobdella valdiviana as having no eyes, other authors have indicated that eyes are indeed present.