Helogenes

Taxobox
name = "Helogenes"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Cetopsidae
subfamilia = Helogeneinae
subfamilia_authority = Regan, 1911
genus = "Helogenes"
genus_authority = Günther, 1863
type_species = "Helogenes marmoratus"
type_species_authority = Günther, 1863
subdivision_ranks = Binomial name
subdivision =
"Helogenes castaneus"
(Dahl, 1960)
"Helogenes gouldingi"
Vari & Ortega, 1986
"Helogenes marmoratus"
Günther, 1863
"Helogenes uruyensis"
Fernández-Yépez, 1967
synonyms = "Leyvaichthys" Dahl, 1960

"Helogenes" is a genus of catfish (order Siluriformes) of the family Cetopsidae. It includes four species, "H. castaneus", "H. gouldingi", "H. marmoratus", and "H. uruyensis".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|format=PDF]

Helogeneinae is the sister taxon of Cetopsinae, the other subfamily in the family Cetopsidae.cite journal|url=http://www.ufrgs.br/ni/vol3num2/Artigo01P127-238lr.pdf|title=The Neotropical whale catfishes (Siluriformes: Cetopsidae: Cetopsinae), a revisionary study|first=Richard P.|last=Vari|coauthors=Ferraris, Carl J.; de Pinna, Mário C. C.|journal=Neotropical Ichthyology|volume=3|issue=2|pages=127–238|year=2005|format=PDF|doi=10.1590/S1679-62252005000200001]

Distribution

"Helogenes" species occur through much of the Amazon River basin, the southern portions of the Orinoco River basin, the coastal rivers of the Guianas, and at least the lower portions of the Tocantins River. "H. castaneus" originates from the Guaviare River and Meta River drainages of the upper [rinoco in eastern Colombia. "H. gouldingi" inhabits the Madeira River basin in Brazil. "H. marmoratus" is found in Atlantic drainages of Guianas, the upper Orinoco and Rio Negro systems, and the upper Amazon River basin. "H. uruyensis" is from the Uruyén River basin in Venezuela.

Description

In "Helogenes", the dorsal fin base is short, the anal fin base is elongate, the dorsal and pectoral fins lack spines, the adipose fin is usually present, but is reduced or absent in one population of one species.cite book|title=Fishes of the World|last=Nelson|first=Joseph S.|publisher=John Wiley & Sons, Inc|year=2006|isbn=0-471-25031-7] cite web|url=http://www.flmnh.ufl.edu/catfish/cetopsidae/intro.htm|title=Whale Catfishes Cetopsidae|first=Carl J.|last=Ferraris, Jr.|coauthors=Vari, Richard P.|date=2007-06-07|accessdate=2007-08-04] "Helogenes" species grow to about 4.3–7.3 centimetres (1.7–2.9 in) SL.FishBase species|genus=Helogenes|species=castaneus|year=2007|month=July] FishBase species|genus=Helogenes|species=gouldingi|year=2007|month=July] FishBase species|genus=Helogenes|species=marmoratus|year=2007|month=July] FishBase species|genus=Helogenes|species=uruyensis|year=2007|month=July]

Ecology

"Helogenes" species feed on allochthonous insects. "H. marmoratus" is nocturnal and feeds mainly on terrestrial insects, particularly ants. "H. gouldingi" has been found in small black-water tributaries. "H. marmoratus" is a typical inhabitant of black or clear waters, usually in forest streams with moderate to swift current flow over firm sand or gravel bottoms .

"H. marmoratus" lives hidden under plants, litter or plant debris. It has a colour pattern that resembles dead leaves. The fish may even lie on its side among the leaf litter as a form of camouflage. It can easily be mistaken as a piece of dead wood when it rests on its side, motionless on the bottom. It often swims on one side in undulating movements. When disturbed, "H. marmoratus" will move upwards through the root-tangle, exposing its head or fore body above the water surface. If disturbed further, it will quickly swim in an upright position towards the nearest debris shelter.cite journal|url=http://www.ufrgs.br/ni/vol4num1%5Cvol4(1)p119.pdf|title=Fallen leaves on the water-bed: diurnal camouflage of three night active fish species in an Amazonian streamlet|first=Ivan|last=Sazima|coauthors=Carvalho, Lucélia Nobre; Mendonça, Fernando Pereira; Zuanon, Jansen|journal=Neotropical Ichthyology|volume=4|issue=1|pages=119–122|year=2006|format=PDF|doi=10.1590/S1679-62252006000100013] Also, "H. marmoratus" is known to jump on the bank during rotenone fishing by Tukano and Tuyuka indigenous people, then jump back to the stream after water renovation.

References