Lithogenes
Encyclopedia
Lithogenes is a genus
of catfish
(order Siluriformes) of the family
Loricariidae
. It is the only genus within the subfamily Lithogeneinae. This genus contains two species
: L. villosus, the type species
, and L. valencia, a possibly extinct
species.
. L. valencia was described in 2003 by Provenzano et al., known by only six specimens.
Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal
group in Loricariidae, is the sister group
to the rest of the family. Relative to an undescribed species
of Lithogeneinae, L. valencia has sister group relationship to L. villosus.
. However, unlike most loricariids, Lithogenes possesses armor plating only on the latter half of the body. Their eyes are small and their bodies flattened.
drainage of the Guiana Shield. An undescribed species of Lithogenes is known from the Orinoco basin of the Guiana Shield. L. valencia has only been known from six specimens collected in the 1970s from tributaries of the Lake Valencia
in north Venezuela
; however, this area has since been polluted and it is possible this species is now extinct.
L. villosus lives in habitats dominated by rapid
s over bedrock
, and it is likely that L. valencia does as well.
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...
(order 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...
Loricariidae
Loricariidae
Loricariidae is the largest family of catfish , with almost 700 species and new species being described each year. Loricariids originate from fresh water habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and...
. It is the only genus within the subfamily Lithogeneinae. This genus contains two species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
: L. villosus, the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, and L. valencia, a possibly extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
species.
Taxonomy
L. villosus was described in 1909 by Carl H. EigenmannCarl H. Eigenmann
Carl 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....
. L. valencia was described in 2003 by Provenzano et al., known by only six specimens.
Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
group in Loricariidae, is the sister group
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
to the rest of the family. Relative to an undescribed species
Undescribed taxon
In taxonomy, an undescribed taxon is a taxon that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. Until such a description has been published, the taxon has no formal or...
of Lithogeneinae, L. valencia has sister group relationship to L. villosus.
Appearance and anatomy
As members of Loricariidae, Lithogenes species have a suckermouthSuckermouth
In fishes, a suckermouth is a ventrally-oriented mouth adapted for grazing on algae and small organisms that grow on submerged objects....
. However, unlike most loricariids, Lithogenes possesses armor plating only on the latter half of the body. Their eyes are small and their bodies flattened.
Distribution and habitat
L. villosus originates from the Essequibo RiverEssequibo River
The Esequibo River is the largest river in Guyana, and the largest river between the Orinoco and Amazon. Rising in the Acarai Mountains near the Brazil-Guyana border, the Essequibo flows to the north for 1,010 km through forest and savanna into the Atlantic Ocean.-Geography:There are countless...
drainage of the Guiana Shield. An undescribed species of Lithogenes is known from the Orinoco basin of the Guiana Shield. L. valencia has only been known from six specimens collected in the 1970s from tributaries of the Lake Valencia
Lake Valencia
Lake Valencia is the third largest lake in Venezuela, exceeded in size only by Lake Maracaibo and Lake Guri. It occupies one of the so-called Aragua valleys, enclosed between the parallel mountain ranges of the Cordillera de la Costa, the Maritime Andes. One part is within the limits of Carabobo...
in north 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...
; however, this area has since been polluted and it is possible this species is now extinct.
L. villosus lives in habitats dominated by rapid
Rapid
A rapid is a section of a river where the river bed has a relatively steep gradient causing an increase in water velocity and turbulence. A rapid is a hydrological feature between a run and a cascade. A rapid is characterised by the river becoming shallower and having some rocks exposed above the...
s over bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
, and it is likely that L. valencia does as well.