''Pseudolithoxus'' is a genus of suckermouth armored catfishes with five described species from the basins of the

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

Casiquiare The Casiquiare river () is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the world's largest ...

and upper Rio Negro in Venezuela. Additionally, a possibly undescribed species is known from the Trombetas and Nhamundá rivers in Brazil.

Taxonomy

The species group was originally described in 2000 and the four species were temporarily placed in '' Lasiancistrus''. In 2001, the genus ''Pseudolithoxus'' was erected for these species. This group forms a

monophyletic 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 ...

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 t ...

to ''Lasiancistrus'' and '' Ancistrus''. ''P. anthrax'' and ''P. nicoi'' likely represent sister species. In 2011, ''P. kelsorum'' was described based on type material from Venezuela.

Species

There are currently five recognized species in this genus: * ''

Pseudolithoxus anthrax ''Pseudolithoxus anthrax'' is a species of armored catfish endemic to Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of Sou ...

'' ( Armbruster &

Provenzano Provenzano is an Italian surname. It may refer to: *Anthony Provenzano (1917–1988), New York mobster * Bernardo Provenzano (1933–2016), member of the Sicilian Mafia *Carmen Provenzano (1942–2005), Canadian politician * Chris Provenzano, Ameri ...

, 2000) * ''

Pseudolithoxus dumus ''Pseudolithoxus dumus'' is a species of armored catfish endemic to Venezuela where it occurs in the Orinoco, Negro and Casiquiare canal The Casiquiare river () is a distributary of the upper Orinoco flowing southward into the Rio Negro, in ...

'' ( Armbruster &

, 2000) * ''

Pseudolithoxus kelsorum ''Pseudolithoxus kelsorum'' is a species of catfish in the family Loricariidae. It is native to South America, where it is known only from a single site in the Orinoco drainage, located above the Maipures Rapids and south of the Atures Rapids (ne ...

'' Lujan & Birindelli, 2011 * ''

Pseudolithoxus nicoi ''Pseudolithoxus nicoi'' is a species of armored catfish endemic to Venezuela where it is found in the upper Negro and Casiquiare canal The Casiquiare river () is a distributary of the upper Orinoco flowing southward into the Rio Negro, in V ...

'' ( Armbruster &

, 2000) * ''

Pseudolithoxus tigris ''Pseudolithoxus tigris'' is a species of armored catfish endemic to Venezuela where it is found in the upper Orinoco and Ventuari River The Ventuari River is the largest tributary of the Orinoco in southern Venezuela. The Ventuari flows from so ...

'' ( Armbruster &

, 2000)

Description

The largest ''Pseudolithoxus'' species reach up to in

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 ...

. The genus is characterized by evertible cheek plates, a very dorsoventrally flattened body, extremely hypertrophied odontodes (integumentary teeth) on elongated pectoral spines and along the snout margin, and 3 rows of plates on the caudal peduncle. In addition, it appears as if females as well as males develop hypertrophied snout and pectoral-fin odontodes, traits normally restricted to nuptial males in other loricariids. ''Pseudolithoxus'' species may be differentiated based on colouration. Two species are black, usually with white spots, and lack dark bands on the caudal fin; ''P. nicoi'' has a white band at the

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

margin of the caudal fin, while ''P. anthrax'' does not. ''P. dumus'' has a colour pattern consisting of black spots on the head and anterior part of body, while ''P. tigris'' has a colour pattern consisting of brown and tan bars on the head and anterior part of body. However, ''P. dumus'' and ''P. tigris'' may actually both represent more species. In ''P. dumus'', specimens from northern Amazonas have a well-spotted caudal peduncle, those from the Ventuari and Cataniapo Rivers have spots along the mid-line on the caudal peduncle, and those from the Casiquiare have spots combining to form bands on the caudal peduncle. In some ''P. tigris'', though specimens have similar colour patterns, they may differ in thickness of the tan bars and dark bars, body depth, and eye position. The body of these fish is very dorsoventrally flattened with both ventral- and dorsal-surface flat. The dorsal fin spine is weak, and the dorsal fin spinelet supports odontodes. The pectoral fins are usually elongated, reaching the anus in juveniles and growing to the anal fins in the adults; ''P. anthrax'' has been referred to as "flying catfish", probably due to these long pectoral fins in adults. The caudal fin is weakly forked, with the lower lobe longer than the upper. The eyes are mostly dorsal. The abdomen is without plates.

References

{{Taxonbar, from=Q929277 Ancistrini Fish of Venezuela Endemic fauna of Venezuela Catfish genera Taxa named by Isaäc J. H. Isbrücker Taxa named by André Werner Freshwater fish genera