Cheirocerus

{{Short description|Genus of fishes}} {{Automatic taxobox | image = Fish species collected from sandy beaches of the Acre river Brazil (4 of 5).png | image_caption = Cheirocerus eques at fig N0. 47 | taxon = Cheirocerus | authority = Eigenmann, 1917 | type_species = ''Cheirocerus eques'' | type_species_authority = Eigenmann 1917 | subdivision_ranks = Species | subdivision = | synonyms = ''Sovichthys'' Schultz, 1944 }}

'''''Cheirocerus''''' is a genus of long-whiskered catfishes native to South America.

==Species== There are currently three recognized species in this genus:<ref>{{FishBase genus | genus = Cheirocerus| month = February | year = 2012}}</ref> * ''Cheirocerus abuelo'' (Schultz, 1944) * ''Cheirocerus eques'' Eigenmann, 1917 * ''Cheirocerus goeldii'' (Steindachner, 1908)

==Distribution and habitat== ''Cheirocerus'' is distributed throughout much of the Amazon River basin, and appear to be absent from the Orinoco River.<ref name=Stewart/> ''C. abuelo'' occurs in the Lake Maracaibo basin, ''C. eques'' in the Amazon River basin, and ''C. goeldii'' in the Purus River basin.<ref name="Ferraris">{{cite journal|url=http://silurus.acnatsci.org/ACSI/library/biblios/2007_Ferraris_Catfish_Checklist.pdf|title=Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types|first=Carl J. Jr.|last=Ferraris|journal=Zootaxa|volume=1418|pages=1–628|year=2007|doi=10.11646/zootaxa.1418.1.1 }}</ref>

''C. goeldii'' is more typical of lowland large rivers where the water may be warmer and deeper, though it may also occur far upstream. ''C. eques'' appears to occur closer to Andean foothills where rivers may be cooler and shallower.<ref name=Stewart/>

==Description== Species of ''Cheirocerus'' have a fully ventral mouth with relatively fleshy lips, a broad premaxilla, a crimped gas bladder that appears to have fringe or finger-like projections, and the slender hollow tube extensions on each side of the gas bladder.<ref name=Stewart>{{cite journal|title=Revision of ''Cheirocerus'' (Pisces: Pimelodidae) from Tropical Freshwaters of South America|first=Donald J.|last=Stewart|jstor=1444845|author2=Pavlik, Michael J.|journal=Copeia|year=1985|issue=2|pages=356–367|doi=10.2307/1444845|volume=1985}}</ref> These fish have an undeveloped dorsal fin locking mechanism and no dorsal fin spine. They also have a relatively long adipose fin.<ref name=Stewart/> These species all have three pairs of barbels.<ref name=Stewart/> ''C. eques'' and ''C. goeldii'' display some geographic variations in certain morphometric characteristics.<ref name=Stewart/>

''C. abuelo'' has a dusky-gray body colouration that varies from relatively plain to having numerous small brown spots, and usually has a broad, diffuse band crossing the nape at the dorsal fin origin. Both ''C. goeldii'' and ''C. eques'' have a relatively uniform body colouration without spots; ''C. goeldii'' has a small, triangular spot at the dorsal fin origin, while ''C. eques'' has a distinct dark band at the dorsal fin origin.<ref name=Stewart/>

''C. abuelo'' appears to attain the largest size of the three species, reaching at least {{convert|22|cm|in}}. By contrast, the largest known ''C. eques'' is about {{convert|14|cm|in}} and the largest ''C. goeldii'' is about {{convert|15|cm|in}}.<ref name=Stewart/>

==Ecology== ''Cheirocerus'' species are generally nocturnal.<ref name=Stewart/> This is evidenced by the specialized gas bladder, hypothesized to enhance hearing, and the poorly developed pigmentation.<ref name=Stewart/>

Diet mostly consists of benthic invertebrates, with chironomid larvae being a dominant component, but also including ostracods and mayfly nymphs.<ref name=Stewart/>

==References== <references/>

Category:Pimelodidae Category:Fish of South America Category:Catfish genera Category:Taxa named by Carl H. Eigenmann Category:Freshwater fish genera