''Denticetopsis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Siluriformes) of the

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

Cetopsidae The Cetopsidae are a small family of catfishes (order Siluriformes), commonly called the whale catfishes. Taxonomy This family contains five genera divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-l ...

Taxonomy

Originally ''Denticetopsis'' as described by Ferraris in 1996 was restricted to two species, ''D. royeroi'' and ''D. sauli''. These two species have proved to be a subunit of a larger

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, ...

that also includes two species previously assigned to the now invalid genus ''Pseudocetopsis'' (''D. macilenta'', ''D. praecox''), together with three species described as new in 2005 (''D. epa'', ''D. iwokrama'', ''D. seducta'').

Species

There are currently seven recognized species in this genus: * '' Denticetopsis epa''

Vari Vari ( el, Βάρη) is a southern suburb of Athens and former municipality in East Attica, Greece along the Athens coast. Since the 2011 local government reform it is part of the municipality Vari-Voula-Vouliagmeni, of which it is a municipal un ...

Ferraris Ferrari Società per Azioni, S.p.A. (; ) is an Italian luxury sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari (1898–1988) in 1939 from the Alfa Romeo racing division as ''Auto Avio Costruzioni'', the company buil ...

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, 2005 * '' Denticetopsis iwokrama''

, 2005 * '' Denticetopsis macilenta'' ( C. H. Eigenmann, 1912) * '' Denticetopsis praecox'' (

& B. A. Brown, 1991) * '' Denticetopsis royeroi''

, 1996 * ''

Denticetopsis sauli ''Denticetopsis sauli'' is a species of whale catfish endemic to Venezuela, where it is only known from the Pamoni River in the Casiquiare River The Casiquiare river () is a distributary of the upper Orinoco flowing southward into the Rio ...

, 1996 * '' Denticetopsis seducta''

, 2005

Distribution

''Denticetopsis'' species are distributed in northern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

where they are found distributed between

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...

and

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Description

''Denticetopsis'' can be distinguished from other genera of Cetopsinae by a number of characteristics. The margin 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 ...

is either shallowly forked and symmetrical or obliquely truncate. The outer most rays are no more than one and one-half times the length of the inner most rays; in other genera of Cetopsinae, these rays are one and three-quarters to two times the length of the innermost rays. The medial most pelvic-fin ray has a membranous attachment to the body for the basal third to fourth of its length instead of the basal-most half of its length. The possession of a first pectoral-fin ray that is spinous for the basal one-half of its length further separates ''Denticetopsis'' from ''Cetopsis'' and ''Paracetopsis'', both of which lack a spinous first pectoral-fin ray. ''Denticetopsis'' is further distinguished from ''

Cetopsidium ''Cetopsidium'' is a genus of catfishes (order Siluriformes) of the family Cetopsidae. Taxonomy ''Cetopsidium'' was described in 2005, its name coming from the ''Cetopsis'', the first described cetopsid genus, and ''idium'' which means diminut ...

'' in the lack of the dorsal-spine locking mechanism and in the having a

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

extending either only onto the abdomen or distinctly further posteriorly onto the

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 se ...

, instead of terminating above the base of the

anal 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 ...

. Most ''Denticetopsis'' have a moderately elongate body (though moderately stout in ''D. macilenta'' and deep in ''D. royeroi'') that is slightly compressed (laterally or transversely, depending on species) anteriorly and becoming progressively distinctly compressed posteriorly. The body depth at the dorsal fin origin is usually about one-quarter of the fish's

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

, but can be as low as one-fifth and as high as almost one-third. In most species, the lateral line is complete, unbranched in midlateral, extending from the vertical through the pectoral fin base to the

; however, in ''D. royeroi'' and ''D. sauli'', it is incomplete, interrupted, and restricted to the abdomen. The dorsal profile of the body tends to be nearly straight to slightly convex; the ventral profile is slightly convex to convex at the abdomen and is usually approximately straight but posterodorsally slanted along the base of the anal fin. Except for ''D. macilenta'' which has a distinctly rounded head and snout, the head of ''Denticetopsis'' species in profile is acutely triangular overall with a bluntly pointed snout. The eyes are situated on the sides of the head and are visible from above but not from below. The mouth is inferior, the width from approximately one-half to two-thirds of the length of the head. In most species of ''Denticetopsis'', the medial mental

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some ...

are slightly shorter than the lateral mental barbels, with the latter approximately equal in length to the slender maxillary barbels. However, in ''C. sauli'' both pairs of mental barbels are approximately the same length and shorter than the maxillary barbels, and in ''C. royeroi'' all three pairs of barbels are approximately the same length. The dorsal fin is moderately large overall. The dorsal fin spinelet is absent. The anal fin base is usually moderately long but may be long. The pelvic fins are usually moderate but may be moderately long, though in ''D. sauli'' they are short. The pectoral fin length is about one-half the length of the head length. ''Denticetopsis'' species range from 1.8–6.7 centimetres (.71–2.6 in) SL.

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 ani ...

in the shape of the dorsal, pectoral, and anal fins has not been described in species of ''Denticetopsis'', despite the presence of these traits in ''Cetopsis'' and ''Cetopsidium''. It is possible that male ''D. praecox'' reach sexual maturity at a smaller size than females of the same species.

Ecology

''D. praecox'' have been found in a cobble-pebble habitat of black water streams that ranged in pH from 4.3–5.0. Stomachs of two examined specimens of this species contained

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

chironomids The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many species s ...

and other larval insect remains.

References

{{Taxonbar, from=Q5259473 Cetopsidae Fish of South America Vertebrates of Guyana Fish of Venezuela Catfish genera Freshwater fish genera