''Sisor'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

es native to

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

Taxonomy

''Sisor'' was previously

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 "unispe ...

, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. torosus'' were described. ''S. barakensis'' was described in 2005. ''S. rabdophorus'' is sometimes spelled ''S. rhabdophorus''; this is meant to correct the misspelling of the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word ''rhabdos'' meaning ''rod''. However, this is not a valid emendation.

Species

There are currently six recognized species in this genus: * ''

Sisor barakensis ''Sisor'' is a genus of catfishes native to Asia. Taxonomy ''Sisor'' was previously monotypic, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. tor ...

'' Vishwanath & Darshan, 2005 * '' Sisor chennuah'' Ng & Lahkar, 2003 * ''

Sisor pakistanicus ''Sisor'' is a genus of catfishes native to Asia. Taxonomy ''Sisor'' was previously monotypic, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. tor ...

'' Javed & Mirza, 2011Javed, M.N. & Mirza, M.R. (2011): Sisor pakistanicus (Teleostei, Sisoridae), a new catfish from the river Chenab, Pakistan.
Biologia (Pakistan), 57 (1&2)
15-21.'' * ''

Sisor rabdophorus ''Sisor'' is a genus of catfishes native to Asia. Taxonomy ''Sisor'' was previously monotypic, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. tor ...

Hamilton Hamilton may refer to: People * Hamilton (name), a common British surname and occasional given name, usually of Scottish origin, including a list of persons with the surname ** The Duke of Hamilton, the premier peer of Scotland ** Lord Hamilto ...

, 1822 * ''

Sisor rheophilus ''Sisor'' is a genus of catfishes native to Asia. Taxonomy ''Sisor'' was previously monotypic, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. tor ...

'' Ng, 2003 * '' Sisor torosus'' Ng, 2003

Distribution and habitat

''Sisor'' species are distributed in the

Ganges The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...

and

Brahmaputra The Brahmaputra is a trans-boundary river which flows through Tibet, northeast India, and Bangladesh. It is also known as the Yarlung Tsangpo in Tibetan, the Siang/Dihang River in Arunachali, Luit in Assamese, and Jamuna River in Bangla. It ...

drainages in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

. ''S. barakensis'' originates from the

Barak River The Barak River flows through the states of Manipur, Nagaland, Mizoram and Assam in India. Further it enters Bangladesh where it bifurcates into the Surma river and the Kushiyara river which converges again to become the Meghna river before f ...

of the Brahmaputra drainage in India. ''S. chennuah'' inhabits the Brahmaputra drainage in

Assam Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...

State, India. ''S. rabdophorus'' originates from the Ganges drainage,

West Bengal West Bengal (, Bengali: ''Poshchim Bongo'', , abbr. WB) is a state in the eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabitants within an area of . West Bengal is the fou ...

States, India. ''S. rheophilus'' originates from the Ganges drainage,

Bihar Bihar (; ) is a state in eastern India. It is the 2nd largest state by population in 2019, 12th largest by area of , and 14th largest by GDP in 2021. Bihar borders Uttar Pradesh to its west, Nepal to the north, the northern part of West ...

and

Uttar Pradesh Uttar Pradesh (; , 'Northern Province') is a state in northern India. With over 200 million inhabitants, it is the most populated state in India as well as the most populous country subdivision in the world. It was established in 195 ...

States, India. ''S. torosus'' lives in the Ganges drainage,

and

Delhi Delhi, officially the National Capital Territory (NCT) of Delhi, is a city and a union territory of India containing New Delhi, the capital of India. Straddling the Yamuna river, primarily its western or right bank, Delhi shares borders w ...

States, India. The identities of ''Sisor'' specimens from the

Indus River The Indus ( ) is a transboundary river of Asia and a trans-Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in Western Tibet, flows northwest through the disputed region of Kashmi ...

Rohini River The Rohni or Rohini or Rohin River rises in the Chure or Sivalik Hills in Kapilvastu and Rupandehi Districts of Nepal's Lumbini Zone and flows south into Uttar Pradesh state, India. At Gorakhpur it becomes a left bank tributary of West Rapti Riv ...

at Madhopur, and

Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...

have not yet been confirmed. ''S. rheophilus'' has been found in fast-moving rivers with sandy bottoms. ''S. rabdophorus'' also inhabits streams with sandy bottoms and strong currents.

Description

''Sisor'' is distinguished from all other erethistids and sisorids by the presence of a series of bony plates extending from the

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

to the base of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

and a spine in

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. Also, the uppermost caudal-fin ray is more than half length of body, the branchiostegal membranes are broadly fused to

isthmus An isthmus (; ; ) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus ...

, the outer and inner mental barbels are widely separated with the origin of outer barbels anterior to origin of inner barbels, the lower jaw teeth are minute, dentition essentially consisting of roughened plate, large serrations on the anterior margin of the pectoral spine (also serrated posteriorly), a well-developed maxillary barbel membrane, and

palatal The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...

teeth absent. The head is moderately narrow and strongly depressed. The body is extremely narrow and strongly depressed. The eyes are small, dorsolaterally located, and under the skin (subcutaneous). The maxillary barbels do not extending beyond the head. The dorsal fin spine is serrate anteriorly and smooth posteriorly. ''S. chennua'', ''S. rheophilus'', and ''S. torosus'' grow to about SL. ''S. rabdophorus'' attains a length of about SL.

References

{{Taxonbar, from=Q5023933 Sisoridae Fish of South Asia Fish of India Fauna of Pakistan Freshwater fish genera Catfish genera Taxa named by Francis Buchanan-Hamilton