Entomocorus

Taxobox
name = "Entomocorus"


image_size = 250px
image_caption = Transformed male "Entomocorus radiosus"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Auchenipteridae
subfamilia = Auchenipterinae
tribus = Auchenipterini
genus = "Entomocorus"
genus_authority = Eigenmann, 1917
type_species = "Entomocorus benjamini"
type_species_authority = Eigenmann, 1917
subdivision_ranks = Species
subdivision =
*"E. benjamini" Eigenmann, 1917
*"E. gameroi" Mago-Leccia, 1984
*"E. melaphareus" Akama & Ferraris, 2003
*"E. radiosus" Reis & Borges, 2006

"Entomocorus" is a genus of catfishes (order Siluriformes) of the family Auchenipteridae.

Taxonomy and phylogeny

"Entomocorus" was first described by Carl H. Eigenmann in 1917 with "E. benjamini" as type species by monotypy. Only a few phylogenetic diagnoses have been presented since.

"Entomocorus" is included as the basal member in the "Auchenipterus"-Group by Carl H. Ferraris; this group also includes "Auchenipterus" and the sister groups "Epapterus" and "Pseudepapterus". This group is sister to the "Ageneiosus"-Group, which includes the genera "Ageneiosus" and "Tetranematichthys". These groups, along with the genus "Trachelyopterus", form the tribe Auchenipterini. However, the placement of "Entomocorus" is problematic due to the loss of some characteristics of that diagnose Auchenipteridae and Auchenipterini. Relationships between species of "Entomocorus" are unknown.

Distribution

"Entomocorus" species are all found in lowland cis-Andean South America. "E. benjamini" is endemic to the upper and middle Madeira River in Brazil and Bolivia. "E. gameroi" occurs in the llanos of the Orinoco River in Venezuela.cite journal|title=The South American Catfish Genus "Entomocorus" (Ostariophysi: Siluriformes:Auchenipteridae), with the Description of a New Species from the Paraguay River Basin|last=Reis|first=Roberto E.|coauthors=Borges, Thiago A. K.|journal=Copeia|year=2006|issue=3|pages=412–422|doi=10.1643/0045-8511(2006)2006 [412:TSACGE] 2.0.CO;2|volume=2006|doilabel=10.1643/0045-8511(2006)2006[412:TSACGE]2.0.CO;2] "E. melaphareus" has been found in the middle and lower Amazon.cite journal|url=http://www.ufrgs.br/ni/vol1num2%5C1(2)artigo01.pdf|title="Entomocorus melaphareus", a new species of auchenipterid catfish (Osteichthyes: Siluriformes) from the lower and middle reaches of the rio Amazonas|last=Akama|first=Alberto|coauthors=Ferraris, Carl H., Jr.|journal=Neotropical Ichthyology|year=2003|volume=1|issue=2|pages=77–82|format=PDF|doi=10.1590/S1679-62252003000200001] "E. radiosus" is endemic to the Mato Grosso Pantanal area in the upper Paraguay River.

Description

"Entomocorus" species are small fish, growing to 5.9–7.0 centimetres SL.FishBase species|genus=Entomocorus|species=benjamini|year=2008|month=January] FishBase species|genus=Entomocorus|species=gameroi|year=2008|month=January] FishBase species|genus=Entomocorus|species=melaphareus|year=2008|month=January] FishBase species|genus=Entomocorus|species=radiosus|year=2008|month=January] Sexual dimorphism is evident in all species except for "E. benjamini"; in this species, transformed males have yet to be found. In the other species, transformed males have stiff, ossified maxillary barbels, an elongated dorsal-fin spine, ventrally-directed pectoral-fin spine hooks, very elongated pelvic-fin unbranched rays, and a rotated anal-fin base.

The four different "Entomocorus" species are not easily distinguished by differences in meristics or morphometrics; however, they are easily be distinguished by pigmentation, especially in caudal fin markings. In "E. benjamini", the distal half of dorsal caudal fin lobe and the edge of the ventral lobe is pigmented. In "E. gameroi", an oblique band crossing from the dorsal profile of the caudal peduncle to the middle-upper rays of the caudal fin. In "E. melaphareus", an inconspicuous patch exists on the dorsal lobe of the caudal fin. In "E. radiosus", the distal half of both the dorsal and ventral caudal fin lobes is pigmented. "E. melaphareus" also has pigmented pectoral and pelvic fins, while these fins in the other three species are unpigmented. "E. radiosus" is the only species that can be diagnosed by meristics; its anal-fin base is longer and has more branched anal-fin rays.

Ecology

"Entomocorus" are nocturnal, pelagic catfish that feed near the surface on invertebrates (primarily insects) and on zooplankton (mainly microcrustaceans). "E. benjamini" has been classified as an invertivore that feeds on aquatic and terrestrial invertebrates (primarily insects), zooplankton (including cladocerans, copepods, and rotiferans), and both aquatic and terrestrial vegetation. "E. gameroi" is classified as an omnivore with a tendency towards insectivory; it has been found to eat cladocerans, copepods, and water mites, as well as ostracods, insects including coleopterans, dipterans, ephemeropterans, hemipterans, and seeds and other vegetal matter. It has been noted that a single fish could ingest as many as 1700 planktonic crustaceans in a single night, when this species feeds near the water surface.cite journal|title=Nocturnal Behavior and Aspects of the Ecology of a Driftwood Catfish, "Entomocorus gameroi" (Auchenipteridae)|first=Marco A.|last=Rodriguez|coauthors=Richardson, Susan E.; Lewis, William M. Jr.|journal=Biotropica|volume=22|issue=4|pages=435–438|year=1990|doi=10.2307/2388565] "E. radiosus" is a zooplanktivore which also eats insects; this species predominantly consumes microcrustaceans (cladocerans, copepods, and ostracods), but also fed on insects (ephemeropterans, coleopterans, and hemipterans).

During the day, "E. gameroi" rests motionlessly. This species has been found to hide among the submerged roots of water hyacinth during the day, but may also use alternative sources of shelter such as wood, rocks, and other benthic substrata in hyacinth-free locations.

The reproductive cycle of "E. gameroi" has been studied, and it is believed that this species is short-lived. Fish of this species reach sexual maturity within a year and perish soon after. Members of a given cohort are never found in the studied lake the next year.

References