''Torix'' is a genus of Rhynchobdellid leeches in the family

Glossiphoniidae Glossiphoniidae are a family of freshwater proboscis-bearing leeches. These leeches are generally flattened, and have a poorly defined anterior sucker. Most suck the blood of freshwater vertebrates like amphibians, crocodilians and aquatic tu ...

, found in Eastern Asia and Japan. ''Rana japonica'', the Japanese brown frog, is the main host of ''T. tagoi.''

''Rickettsia'' bacterial infection

Two members of the genus, ''T. tagoi'' and ''T. tukubana'', show high percentages of ''

Rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "rickett ...

'' infection in the wild; 96% and 83% respectively, according to a 2003 study. Eggs of ''T. tagoi'' were found to all contain the bacteria, indicating the bacteria is almost always passed on to the next generation (

vertical transmission Vertical transmission of symbionts is the transfer of a microbial symbiont from the parent directly to the offspring. Many metazoan species carry symbiotic bacteria which play a mutualistic, commensal, or parasitic role. A symbiont is acquire ...

). It was found that infected leeches grew far larger than those uninfected with the bacteria. Another paper concluded that the ''Rickettsia'' that acted as endosymbionts in the leeches represented a separate

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

of ''Rickettsia'', named the ''torix'' clade. As ''T. tagoi'' feeds on the blood of amphibians such as frogs and newts, it is possible that those amphibians were the route of horizontal transmission.

Species

Torix imported from iNaturalist photo 2613209 on 11 December 2022

The number of species the genus contains is somewhat disputed between taxonomic databases and scientific papers. * '' Torix cotylifer'' Blanchard, 1898 * '' Torix mirus'' Blanchard, 1893 * '' Torix novazealandiae'' (Dendy & Olliver, 1900) * '' Torix orientalis'' (Oka, 1925) * '' Torix tagoi'' (Oka, 1925) * '' Torix tukubana'' (Oka, 1935) '' Torix baicalensis'' was moved to the genus ''Glossiphonia''.

References

Glossiphoniidae Annelid genera Fauna of Asia {{Annelid-stub