genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
catfish
Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...
es (
order
Order, ORDER or Orders may refer to:
* A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
...
Siluriformes) of the
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Akysidae
The stream catfishes comprise the family Akysidae of catfishes.
Distribution and habitat
Akysids are known from across a large area in Southeast Asia. They are found in fresh water. Fish of the subfamily Parakysinae are primarily found in the Mal ...
.
Taxonomy
In 1996, it was determined that ''Akysis'' is the
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to all other akysids, then only including ''
Parakysis
''Parakysis'' is a genus of catfishes (order Siluriformes) of the family Akysidae. It includes six species.
Distribution
''Parakysis'' species are found in small forest streams of Sundaic Southeast Asia. ''P. anomalopteryx'' originates from th ...
'', ''
Acrochordonichthys
''Acrochordonichthys'' is a genus of catfishes ( order Siluriformes) of the family Akysidae. It includes ten species.
Distribution and habitat
''Acrochordonichthys'' species are generally found at the bottoms of rivers throughout Southeast As ...
'', and ''
Breitensteinia
''Breitensteinia'' is a genus of catfishes (order Siluriformes) of the family Akysidae. It includes three species.
Taxonomy
''B. insignis'' was first described for an unusual akysid by Franz Steindachner in 1881. The genus had been monotypic si ...
''. However, it was acknowledged that the genus ''Akysis'' was poorly sampled at the time and may be deemed non-
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
in the future.
In 1998, it was recognized that the large genus ''Akysis'' includes two species groups. The first species group was the ''Akysis variegatus'' group, for species more closely related to the
type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
; the other group was the ''pseudobagarius'' group for species more closely related to the formerly-named ''Akysis pseudobagarius''; the authors recognized it as conceivable that the groups represented two genera, but tentatively retained the species in a single genus. Since then, the genus ''
Pseudobagarius
''Pseudobagarius'' is a genus of catfishes (order Siluriformes) of the family Akysidae.
Taxonomy
''Pseudobagarius'' includes species that were originally part of the ''pseudobagarius'' group of the genus ''Akysis''. This group was first recogniz ...
'' was erected for this species group, leaving only members of the ''A. variegatus'' group in the genus ''Akysis''.
In 2007, ''Laguvia manipurensis'' was redescribed to the genus ''Akysis'' as part of the ''A. variegatus'' group.
Distribution
These fish are found in fast-flowing streams in
Southeast Asia
Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
. This area is bordered by the
Irrawaddy River
The Irrawaddy River (, , Ayeyarwady) is the principal river of Myanmar, running through the centre of the country. Myanmar’s most important commercial waterway, it is about 1,350 miles (2,170 km) long. Originating from the confluence of the ...
drainage to the west, the
Barito River
The Barito River is the second longest river in Borneo, Indonesia after the Kapuas River with a total length of and a drainage basin of over in South Kalimantan, Indonesia. It originates in the Müller Mountain Range, from where it flows ...
drainage to the east, the Lancangjiang (upper
Mekong
The Mekong or Mekong River ( , ) is a transboundary river in East Asia and Southeast Asia. It is the world's twelfth-longest river and the third-longest in Asia with an estimated length of and a drainage area of , discharging of wat ...
) drainage to the north, and the
Citarum River
The Citarum River (more correctly called the Tarum River, as the prefix "Ci" simply means "river") () is the longest and largest river in West Java, Indonesia. It is the third longest river in Java, after Bengawan Solo and Brantas. It plays an i ...
drainage to the south. ''Akysis'' have been reported from
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
,
Sumatra
Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...
,
Borneo
Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...
Thailand
Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
,
Myanmar
Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
, and, most recently, the distribution of ''Akysis'' has been discovered to include
India
India, officially the Republic of India, 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 by population (United Nations), most populous country since ...
.
Description
These small
catfish
Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...
can be distinguished by their general colouring of yellow markings on a brown background. Fishes of the genus ''Akysis'' are diagnosed by having tough leathery skin covered with
tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projectio ...
s which are arranged in longitudinal rows along the sides, the anterior margin of the pectoral spine with a notch visible dorsally, the nasals with expansions beyond the canal-bearing teeth, and no palatal teeth. These fish are distinguished from the members of the genus ''
Pseudobagarius
''Pseudobagarius'' is a genus of catfishes (order Siluriformes) of the family Akysidae.
Taxonomy
''Pseudobagarius'' includes species that were originally part of the ''pseudobagarius'' group of the genus ''Akysis''. This group was first recogniz ...
'' by a number of characteristics: these species have a terminal mouth; the posterior and anterior nostrils being smaller and located further apart with a distance between the base of the nasal barbel and anterior nostril; the anterior nostrils are situated at the tip of a short tube; and the caudal fin is truncate or emarginate rather that forked.
The maximum adult size of ''Akysis'' species is less than 70 millimetres (2.8 in) SL.
Ecology
Catfishes of the genus ''Akysis'' are small cryptically-coloured species. ''Akysis'' are small secretive fishes that occupy a variety of habitats. Most species typically inhabit clear swift-flowing upland streams with sandy or rocky substrates. Some species are reported from the muddy side and main channels and deltas of large rivers. In smaller streams they may be found hiding in leaf litter and woody debris, in patches of live vegetation such as '' Cryptocoryne affinis'', or in shallow riffle areas under coarse gravel or larger stones. Species of ''Akysis'' also are reported from the shallow margins to the bottom depths of large rivers where they are usually taken in trawls together with decaying vegetation.
Page
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