Genus of fishes
Hemiancistrus is a genus of suckermouth armored catfishes. These species are native to South America. The taxonomy of this genus is complex and unclear, and major work has to be done. Many of these fish are popular aquarium fish.
Taxonomy.
"Hemiancistrus" is a genus within the tribe Ancistrini of the subfamily Hypostominae. This genus has long been used as a "dump" for Loricariid species; fish with unclear relationships have been classified as members of this genus. As such, this taxon is not monophyletic. At this point, many undescribed species remain.
This genus and the closely related "Peckoltia" may be synonymous, as neither genus is supported by synapomorphies. "Hemiancistrus" species differ from other members of the "Panaque" clade lacking the synapomorphies of the other genera and having the dentaries meeting at an angle greater than 120°; in "Peckoltia" species, the dentaries meet at less than 90° Generally, "Peckoltia" are considered to be those that have dorsal saddles and bands in the fins, while "Heminancistrus" have spots and uniform coloration.
What species belong to this genus has been unclear. Many newer species have been tentatively assigned to "Hemiancistrus". Although the recently described "H. micrommatos" and "H. spinosissimus" have been considered synonyms of "H. spilomma" by Armbruster, they have more recently been considered valid. "H. micrommatos", "H. spinosissimus" and "H. spilomma" are currently placed in the genus "Ancistomus". "Hemiancistrus medians" is larger than most species that were left in "Hemiancistrus", has well-developed keels (only present elsewhere in H.' landoni"), and a different body shape. The remainder of the taxa that do not have established genera that they can be placed in will be recognized as species groups in Hemiancistrus"' in single quotes until they can be examined further.
Species.
There are currently 15 recognized species in this genus:
Distribution and habitat.
"Hemiancistrus" species are mainly found in tropical and subtropical South America east of the Andes, but there is also species ("'H.' landoni") in Pacific coast drainages of Colombia and Ecuador. The genus exhibits a large distribution area ranging from the Panama, in Central America, to southern Brazil. Many "Hemiancistrus" originate from the Guyanas, the Negro and Orinoco and the southern Amazonian tributaries. These fish prefer flowing water habitats of medium to large rivers.
Appearance and anatomy.
"Hemiancistrus" are members of the family Loricariidae, the armored suckermouth catfishes. As such, they have armor plating on their body instead of scales. Also, they have a suckermouth which they use to cling to rocks in their habitat. They have the characteristic Loricariid "omega iris" as well. Like many other catfish, "Hemiancistrus" have strong pectoral and dorsal fin spines that can be locked outwards as a defense.
"Hemiancistrus" species are rather small to medium-sized Loricariid species. The largest species of the genus, "'H.' megalopteryx", reaches about . These fish also tend to be spotted or uniform in coloration.
In the aquarium.
"Hemiancistrus" species are popular aquarium fish. Many species are relatively small and attractively colored. Hemiancistrus' subviridis" is one such example, a bright green fish with yellow spots. However, H.' guahiborum" is only rarely imported; despite being common in its natural habitat, it is less attractive than "'H.' subviridis", which occurs in the same area.
References.
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