''Breitensteinia'' is a

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 ...

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 ...

. It includes three

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

Taxonomy

''B. insignis'' was first described for an unusual akysid by

Franz Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner des ...

in 1881. The genus had been

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 "unisp ...

since its description until a revision in 1998, along with the description of the two species ''B. cessator'' and ''B. hypselurus''. This genus stands out as derived among the akysids due to the large increase in vertebrae count. ''B. insignis'' and ''B. cessator'' are more closely related to one another than to ''B. hypselurus'', 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 the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

formed by the former two species.

Species

* '' Breitensteinia cessator'' Ng & Siebert, 1998 * '' Breitensteinia hypselurus'' Ng & Siebert, 1998 * '' Breitensteinia insignis''

Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner descri ...

, 1881

Distribution and habitat

''Breitensteinia'' species inhabit the middle and upper reaches of rivers in

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 ...

and

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. ...

. ''B. cessator'' is known from the Batang Hari and Tulangbawan drainages in Sumatra and the

Kapuas River The Kapuas River ( Old Indonesian spelling: Kapoeas River) is a river in the Indonesian part of Borneo island, at the geographic center of Maritime Southeast Asia. At in length, it is the longest river on the island of Borneo, the longest ri ...

drainage in western Borneo. ''B. hypselurus'' is known only from the Kapuas River basin in western Borneo. ''B. insignis'' comes from 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 of southern Borneo.

Description

''Breitensteinia'' is a genus of akysid catfish lacking an

adipose fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

but having a long low adipose ridge, with a very long and slender

caudal peduncle Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

, with the

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

openings not extending above the base of the pectoral spine, with 11–12 principal caudal-fin rays, and with 42–45

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e. Like other akysids and unusually among catfish, they have a low principal caudal fin ray count and more rays in the upper caudal fin lobe than the lower. They have an elongate body, reflected by their high number of vertebrae which is eight to twelve more than in other akysid species, a clear sign of

monophyly 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 comm ...

. ''Breitensteinia'' species have a head that is depressed, broad, and covered with small

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, a tubular anterior nostril, a narrow

occipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lobes of the cere ...

process with its tip tapering and reaching predorsal plate, a body with tubercles arranged in five to six longitudinal rows on each side, a dorsal profile rising evenly but not steeply from the tip of snout to the origin of dorsal fin and then sloping gently ventrally from there to the

, a horizontal ventral profile to the origin of the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

and then rising to the caudal peduncle, a dorsal fin origin nearer to the tip of the snout than caudal flexure, and a truncate caudal fin. ''B. hypselurus'' has a smooth posterior edge to its dorsal fin spine, relatively tall neural spines on the caudal vertebrae, a shorter caudal peduncle, a longer snout, greater distance between the eyes, and fewer vertebrae than the other two species. Between ''B. insignis'' and ''B. cessator'', ''B. cessator'' has larger eyes, greater distance between the eyes, and evenly scattered brown spots on the dorsal and pectoral fins, while ''B. insignis'' has smaller eyes, less distance between the eyes, and the brown spots on dorsal and pectoral fins concentrated in a dark band near the edges. ''B. cessator'' grows to about 7.5 centimetres (3.0 in) SL. ''B. hypselurus'' grows to about 12.2 cm (4.8 in) SL. ''B. insignis'' grows to about 22.0 cm (8.7 in) SL. The dorsal surface of the head is brown, with dark-brown spots scattered randomly throughout. The dorsolateral and lateral surfaces of the body are dark brown with spots on the dorsolateral surface extending from the predorsal area to the base of the caudal fin. The adipose ridge is light brown. In ''B. cessator'' and ''B. insignis'', a small patch of light brown is occasionally present on the predorsal area. The belly, chest, and ventral surface of the head is cream or light brown, with a few scattered brown spots in ''B. insignis''. In ''B. cessator'', the dorsal and pectoral fins are cream with numerous brown spots scattered throughout and the pelvic and anal fins are cream with one or two dark-brown bands, one present occasionally at the base of the fins and another in the distal half of the fins; in ''B. hypselurus'' and ''B. insignis'', the dorsal, pectoral, pelvic, and anal fins are cream with a dark-brown band in the distal half of the fins. The caudal fin is cream with a dark brown band in the distal half and with a narrow midlateral prolongation. The barbels and pectoral spines are cream or light brown, with dark-brown spots, only present sometimes on the dorsal surfaces in ''B. cessator'' and ''B. insignis''.

Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

is exhibited by ''B. insignis''. Males have the anus situated immediately in front of a genital papilla, which is located immediately posterior to the pelvic-fin base. The genital opening is situated at the tip of the papilla, covered by a fleshy flap. In females, the anus is situated more posteriorly and the genital opening is located at the tip of a short genital appendage. The pelvic fins of females are also more closely set.

Ecology

Prawn Prawn is a common name for small aquatic crustaceans with an exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the intern ...

s are included in the diet of these fish. ''Breitensteinia'' species may moult their skin. This is accompanied by a temporary loss of pigmentation.

References

{{Taxonbar, from=Q4960445 Akysidae Fish of Southeast Asia Fish of Indonesia Catfish genera Taxa named by Franz Steindachner Freshwater fish genera