''Tyrannobdella'' is a monotypic genus of

leech Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodie ...

, of family

Praobdellidae Praobdellidae is a family of hematophagous leeches which live on the mucous membranes of mammals and sometimes invertebrates. These are internal parasites that enter the body through natural orifices (usually nasal cavities and pharynx, more rar ...

, found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

in the upper reaches of the Amazon. This newly found

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of leech takes sustenance from the mucous membranes of the mammalian upper respiratory tract, and is known to feed upon humans. It has eight teeth. ''Tyrannobdella rex'' was discovered feeding upon the mucous membrane of a girl who had recently bathed in the upper Amazon in

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

. Genetic studies show that it is closely related to '' Dinobdella ferox'', a similar species found in

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

Characteristics

Unlike related leeches, ''Tyrannobdella rex'' has a single jaw with one row of teeth. Its eight teeth are disproportionately large, with a length of up to 0.13 mm, which inspired discoverers of the species to use a name reminiscent of '' Tyrannosaurus rex''. These teeth are about five times as long as those in the related genus ''Limnatis''; most often one will only see six teeth of ''T. rex'' with a microscope as the others are subcutaneous. The closely related leech ''Pintobdella chiapasensis'' features a likewise reduced number of teeth, namely six per jaw, but in turn it has three jaws.

Life and diet

As a juvenile, ''T. rex'' will bite into the mucous membranes (mucosae) of its host and feed on their blood. In contrast to other leeches, ''T. rex'' does not drop off its host after feeding but can remain attached at the site of its bite for days and weeks. After a time it can reach a length of up to 7 cm. ''Tyrannobdella rex'' favours the mucosae of mouth, nose and throat in humans. Other leeches that also settle in mucosae have been found in noses but as well near the eyes and in the

genitourinary system The genitourinary system, or urogenital system, are the organs of the reproductive system and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathwa ...

of mammals.

Symptoms

When ''Tyrannobdella rex'' inhabits the

nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal c ...

it can cause strong headaches. Because of its small size the leech is most often not discovered immediately.

Taxonomy

The characteristical single jaw in this leech has led to the establishment of a new genus ''Tyrannobdella'', of which only ''T. rex'' is known so far. A genus with only one species is called

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

. The finding of ''Tyrannobdella rex'' and genetic comparisons of its genome to other leeches that infest the mucosae of mammals has brought new insight to their taxonomy. ''T. rex'' was put into the family Praobdellidae, which also includes the genera ''Praobdella'', ''Pintobdella'', ''Myxobdella'', ''Dinobdella'', ''Limnatis'', and ''Limnobdella''. Most of these are found in Africa and Asia, ''Tyrannobdella rex'' being the only one from South America. Its closest relative, ''Pintobdella chiapasensis'', is native to

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, where it infests

tapir Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inhabit ...

s. The sister group to Praobdellidae is made up of the two South American families Semiscolescidae (genera '' Semiscolex'' and '' Patagoniobdella'') and

Macrobdellidae Macrobdellidae is a family of Nearctic leeches belonging to the order Arhynchobdellida Arhynchobdellida, the proboscisless leeches, are a monophyletic order of leeches. They are defined by the lack of the protrusible proboscis that defines the ...

(genera ''

Macrobdella ''Macrobdella'' is a genus of leeches native to freshwater ecosystems of North America, especially Canada, Mexico, and the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or Am ...

'', ''

Philobdella ''Philobdella''Verrill AE (1874) Synopsis of North American freshwater leeches. ''United States Fisheries Commission Report for 1872–73, Pt. 2.'' 666–689. is a genus of Nearctic leeches belonging to the family Macrobdellidae. Species ITIS in ...

'' and '' Oxyptychus'').

References

{{Taxonbar, from1=Q18644998, from2=Q287277 Leeches Annelid genera Monotypic protostome genera