Cetopsis
Encyclopedia
Cetopsis is a genus
of catfish
es (order
Siluriformes) of the family
Cetopsidae
.
with Cetopsis to retain monophyly
of cetopsine genera without erecting many new ones.
Information on some species is limited due to lack of specimens. C. caiapo, C. jurubidae, C. sarcodes, and C. umbrosa are only known from a single specimen each, C. starnesi is only known from two specimens, C. parma is only known from four, and C. sandrae from only six specimens.
, including the Amazon
, Atrato
, Madeira
, Magdalena
, Orinoco
, Tocantins
, and other rivers in Bolivia
, Brazil
, Colombia
, Ecuador
, Peru
, and Venezuela
.
, the absence of spines on the dorsal and pectoral fins, and the possession of a single row of teeth on the vomer
.
Like most other members of the subfamily Cetopsinae, mature males in most species have the distal ends of the first rays of the dorsal and pectoral fins elongated into filaments and a convex (vs. straight) margin to the anal fin. Unlike all other species, in C. coecutiens, the fin ray filaments are present in both sexes and this species must be differentiated by the anal fin. In C. oliveirai, the fin ray filaments are much longer than in other species, however there is also no difference between the sexes in either the fin ray filament lengths or the anal fin margin. The presence of these traits in mature males cannot be confirmed in C. amphiloxa, C. caiapo, C. jurubidae, C. parma, due to the small number of specimens. The one specimen of C. sarcodes is probably an immature male based on the form of its genital papilla, though it lacks the fin ray elongations and convex anal fin margin of mature males.
Colour patterns vary between species. C. amphiloxa has very small spots on the dorsal and lateral surfaces of the body, while C. montana, C. plumbea, C. starnesi, and C. umbrosa have eye-sized spots on the lateral surfaces of the body. C. arcana, C. caiapo, C. orinoco, C. parma, C. sarcodes have a dark humeral spot (a spot in the shoulder region). C. arcana, C. montana, C. pearsoni, C. sandrae, C. starnesi, and C. umbrosa have a posteriorly-rounded, variably-developed, bilobed patch of dark pigmentation at the base of the caudal fin. C. fimbriata have a band of dark pigmentation along the distal portions of the anal fin. C. motatanensis has a caudal fin darkly pigmented throughout other than for a narrow pale distal margin, while C. orinoco has dark pigmentation on the caudal fin particularly on the distal portions of the fin.
The body of Cetopsis species ranges from slender to stout. Unlike all other species, C. candiru has incisiform (vs. conical) teeth on the vomer
and dentary, and also has a more slender body than all other species. Unlike all other species, C. coecutiens has transverse, slit-like psoterior nares rather than rounded posterior nares. The eye is completely absent in C. oliveirai; the eye, present to some degree in all other species of Cetopsis, is situated on the lateral surface of the head and is visible from above but not below. In most species, the mouth is inferior and the width is one-half the length of the head; the margin of the lower jaw is often gently to broadly rounded. The mental barbels
are almost always approximately the same size and length to each other and often the same length as or sometimes shorter than the slender and short maxillary barbels. In most species, the dorsal fin is moderately large, but in C. caiapo and C. parma, it is relatively small. The caudal fin is shallowly- to deeply-forked and symmetrical (though apparently asymmetrical in C. jurubidae), the ends of the lobes usually pointed, bluntly pointed, or rounded (however, the tips are damaged in the single specimen of C. umbrosa). The base of the anal fin is moderate to long, though is relatively short in some species. The pelvic fin ranges from short to moderate to large. The pectoral fin length is usually two-thirds of the length of the head.
C. oliveirai has been found to be a paedomorphic species of the genus Cetopsis, with many traits similar to juveniles of C. coecutiens.
region of the upper Tocantins River basin in both epigean and subterranean waters. C. baudoensis has been found in a highly turbid, white-water river over clay bottoms with logs in the main channel and clay and leaves in the lower portions of the quebradas that were tributary to the main river channel. Specimens were collected at depths of 2 m or less and at an elevation of less than 50 m. C. motatanensis is found in swiftly flowing water among rubble to coarse gravel. C. oliveirai originates in white water systems at depths of 2–40 m and feeds on terrestrial arthropod
s. C. orinoco reportedly inhabits the middle portions of the water column of high-velocity streams during the night and hides among submerged branches and other obstructions in the river channel during the day. C. plumbea is reported to feed on a variety of terrestrial and aquatic insect
s. It inhabits streams with moderate current and a depth of up to 1 m, occurring within such streams in areas over sand substrates but lacking vegetation. C. sandrae was found in riffles in a relatively fast-flowing forest stream, approximately 3–4 m wide and 0.4–0.8 m deep with a small waterfall.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of catfish
Catfish
Catfishes 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 heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
es (order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Siluriformes) of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Cetopsidae
Cetopsidae
Cetopsidae is a small family of catfishes , commonly called the whale catfishes.-Taxonomy:This family contains five genera. It is divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-level group, but now it has been reclassified as a subfamily of Cetopsidae...
.
Taxonomy
Cetopsis is one of four genera in the subfamily Cetopsinae within the family Cetopsidae. Cetopsis is greatly expanded from when it only included C. coecutiens. A number of genera were synonymizedSynonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Cetopsis to retain monophyly
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
of cetopsine genera without erecting many new ones.
Information on some species is limited due to lack of specimens. C. caiapo, C. jurubidae, C. sarcodes, and C. umbrosa are only known from a single specimen each, C. starnesi is only known from two specimens, C. parma is only known from four, and C. sandrae from only six specimens.
Distribution
Cetopsis species are found in major freshwater rivers draining to the east and west of South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, including the Amazon
Amazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
, Atrato
Atrato River
The Río Atrato is a river of northwestern Colombia. It rises in the slopes of the Western Cordillera and flows almost due north to the Gulf of Urabá , where it forms a large, swampy delta....
, Madeira
Madeira River
The Madeira River is a major waterway in South America, approximately 3,250 km miles long The Madeira is the biggest tributary of the Amazon...
, Magdalena
Magdalena River
The Magdalena River is the principal river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of its lower reaches, in spite of the shifting sand bars at the mouth of its delta, as...
, Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...
, Tocantins
Tocantins River
The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...
, and other rivers in Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
.
Description
Cetopsis is distinguished from the other genera in the Cetopsinae from the combination of the absence of a spinelet associated with the dorsal finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
, the absence of spines on the dorsal and pectoral fins, and the possession of a single row of teeth on the vomer
Ichthyology terms
Ichthyology uses several terms that are unique to the science.Contents: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z- A :* Abdomen: belly* Abdominal: pertaining to the belly* Actinosts: a series of bones at the base of the pectoral rays....
.
Like most other members of the subfamily Cetopsinae, mature males in most species have the distal ends of the first rays of the dorsal and pectoral fins elongated into filaments and a convex (vs. straight) margin to the anal fin. Unlike all other species, in C. coecutiens, the fin ray filaments are present in both sexes and this species must be differentiated by the anal fin. In C. oliveirai, the fin ray filaments are much longer than in other species, however there is also no difference between the sexes in either the fin ray filament lengths or the anal fin margin. The presence of these traits in mature males cannot be confirmed in C. amphiloxa, C. caiapo, C. jurubidae, C. parma, due to the small number of specimens. The one specimen of C. sarcodes is probably an immature male based on the form of its genital papilla, though it lacks the fin ray elongations and convex anal fin margin of mature males.
Colour patterns vary between species. C. amphiloxa has very small spots on the dorsal and lateral surfaces of the body, while C. montana, C. plumbea, C. starnesi, and C. umbrosa have eye-sized spots on the lateral surfaces of the body. C. arcana, C. caiapo, C. orinoco, C. parma, C. sarcodes have a dark humeral spot (a spot in the shoulder region). C. arcana, C. montana, C. pearsoni, C. sandrae, C. starnesi, and C. umbrosa have a posteriorly-rounded, variably-developed, bilobed patch of dark pigmentation at the base of the caudal fin. C. fimbriata have a band of dark pigmentation along the distal portions of the anal fin. C. motatanensis has a caudal fin darkly pigmented throughout other than for a narrow pale distal margin, while C. orinoco has dark pigmentation on the caudal fin particularly on the distal portions of the fin.
The body of Cetopsis species ranges from slender to stout. Unlike all other species, C. candiru has incisiform (vs. conical) teeth on the vomer
Vomer
The vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.-Biology:...
and dentary, and also has a more slender body than all other species. Unlike all other species, C. coecutiens has transverse, slit-like psoterior nares rather than rounded posterior nares. The eye is completely absent in C. oliveirai; the eye, present to some degree in all other species of Cetopsis, is situated on the lateral surface of the head and is visible from above but not below. In most species, the mouth is inferior and the width is one-half the length of the head; the margin of the lower jaw is often gently to broadly rounded. The mental barbels
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
are almost always approximately the same size and length to each other and often the same length as or sometimes shorter than the slender and short maxillary barbels. In most species, the dorsal fin is moderately large, but in C. caiapo and C. parma, it is relatively small. The caudal fin is shallowly- to deeply-forked and symmetrical (though apparently asymmetrical in C. jurubidae), the ends of the lobes usually pointed, bluntly pointed, or rounded (however, the tips are damaged in the single specimen of C. umbrosa). The base of the anal fin is moderate to long, though is relatively short in some species. The pelvic fin ranges from short to moderate to large. The pectoral fin length is usually two-thirds of the length of the head.
C. oliveirai has been found to be a paedomorphic species of the genus Cetopsis, with many traits similar to juveniles of C. coecutiens.
Ecology
C. arcana was collected in a karsticKarst topography
Karst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...
region of the upper Tocantins River basin in both epigean and subterranean waters. C. baudoensis has been found in a highly turbid, white-water river over clay bottoms with logs in the main channel and clay and leaves in the lower portions of the quebradas that were tributary to the main river channel. Specimens were collected at depths of 2 m or less and at an elevation of less than 50 m. C. motatanensis is found in swiftly flowing water among rubble to coarse gravel. C. oliveirai originates in white water systems at depths of 2–40 m and feeds on terrestrial arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s. C. orinoco reportedly inhabits the middle portions of the water column of high-velocity streams during the night and hides among submerged branches and other obstructions in the river channel during the day. C. plumbea is reported to feed on a variety of terrestrial and aquatic insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. It inhabits streams with moderate current and a depth of up to 1 m, occurring within such streams in areas over sand substrates but lacking vegetation. C. sandrae was found in riffles in a relatively fast-flowing forest stream, approximately 3–4 m wide and 0.4–0.8 m deep with a small waterfall.
Species
Species list according to Vari, Ferraris & de Pinna, 2005.- Cetopsis amphiloxa (EigenmannCarl H. EigenmannCarl H. Eigenmann was an ichthyologist who, along with his wife Rosa Smith Eigenmann, described many of the fishes of North America and South America for the first time....
, 1914) - Cetopsis arcana Vari, Ferraris & de Pinna, 2005
- Cetopsis baudoensis (Dahl, 1960)
- Cetopsis caiapo Vari, Ferraris & de Pinna, 2005
- Cetopsis candiru SpixJohann Baptist von SpixDr. Johann Baptist Ritter von Spix was a German naturalist.Spix was born in Höchstadt, Middle Franconia, as the seventh of eleven children. His boyhood home is the site of the Spix Museum , opened to the public in 2004...
& AgassizLouis AgassizJean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...
, 1829 - Cetopsis coecutiens (LichtensteinMartin LichtensteinMartin Hinrich Carl Lichtenstein was a German physician, explorer, zoologist, and herpetologist.-Biography:...
, 1819) - Cetopsis fimbriata Vari, Ferraris & de Pinna, 2005
- Cetopsis gobioides Kner, 1858
- Cetopsis jurubidae (FowlerHenry Weed FowlerHenry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...
, 1944) - Cetopsis montana Vari, Ferraris & de Pinna, 2005
- Cetopsis motatanensis (Schultz, 1944)
- Cetopsis oliveirai (Lundberg & Rapp Py-Daniel, 1994)
- Cetopsis orinoco (Schultz, 1944)
- Cetopsis othonops (Eigenmann, 1912)
- Cetopsis parma Oliveira, Vari & Ferraris, 2001
- Cetopsis pearsoni Vari, Ferraris & de Pinna, 2005
- Cetopsis plumbea SteindachnerFranz SteindachnerFranz Steindachner was an Austrian zoologist.- Work and career :Being interested in natural history, Steindachner took up the study of fossil fishes on the recommendation of his friend Eduard Suess...
, 1882 - Cetopsis sandrae Vari, Ferraris & de Pinna, 2005
- Cetopsis sarcodes Vari, Ferraris & de Pinna, 2005
- Cetopsis starnesi Vari, Ferraris & de Pinna, 2005
- Cetopsis umbrosa Vari, Ferraris & de Pinna, 2005