''Breitensteinia'' 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 ( order Siluriformes) of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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 In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

Taxonomy

''B. insignis'' was first described for an unusual akysid by Franz Steindachner 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 "unispe ...

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 Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

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 to the clade formed by the former two species.

Species

* '' Breitensteinia cessator'' Ng & Siebert, 1998 * '' Breitensteinia hypselurus'' Ng & Siebert, 1998 * '' Breitensteinia insignis'' Steindachner, 1881

Distribution and habitat

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

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...

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

Kapuas River The Kapuas River (or 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 in the island of Borneo and the longest river of IndonesiaMacK ...

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 after the Kapuas River with a total length of and with a drainage basin of in South Kalimantan, Indonesia. It originates in the Muller Mountain Range, from where it flows southward in ...

drainage of southern Borneo.

Description

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

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 ...

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

caudal peduncle 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 see ...

, with the

gill A gill () is a respiratory organ that many 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 respiration on land provided they are ...

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

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

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 cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. ''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 projection ...

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 overlies the occipital lobes of the cereb ...

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 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 the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

is exhibited by ''B. insignis''. Males have the anus situated immediately in front of a

genital papilla The genital papilla is an anatomical feature of the external genitalia of some animals. In mammals In mammals, the genital papilla is a part of female external genitalia not present in humans, which appears as a small, fleshy flab of tissue. The p ...

, 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 and ten legs (which is a member of the order decapoda), some of which can be eaten. The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature' ...

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