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Helogenes


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.

Helogeneinae is the sister taxon of Cetopsinae, the other subfamily in the family Cetopsidae.

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 Uruyen 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. Helogenes species grow to about 4.3–7.3 centimetres SL.

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. 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.

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Helogenes


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