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Rhyacoglanis paranensis Shibatta & Vari, 2017   


hyacoglanis
, a new genus of the South American freshwater catfish family Pseudopimelodidae is described from cis-Andean portions of the continent and was only described this year (2017) and so this new genus and species is our subject for our July 2017 factsheet.

 

Rhyacoglanis paranensis

 

Rhyacoglanis paranensis

 

This new genera and species has a long chequered past with the first pictures of this species appearing in the 3rd volume of Catfishes of the World (Auchenipteridae and Pimelodidae) By David Sands as far back as 1984 with David having importing them 5 years previously from Sao Paulo in 1979. You have to remember that the Pseudopimelodidae had yet to be assigned by Lundberg, Bornbusch & Mago-Leccia, 1991 as a sub-family of Pimelodidae.

 

Rhyacoglanis is distinguished from other genera of the family by three synapomorphies: presence of a light blotch on the cheek; a connection between the middle of the dark caudal-fin stripe and the dark caudal-peduncle pigmentation; and 30-35 total vertebrae. Species of Rhyacoglanis are rheophilic and strongly associated with rapids and other swift-flowing waters. A phylogenetic analysis based on 41 morphological characters yields a hypothesis of monophyly of the Pseudopimelodidae and Rhyacoglanis. Pimelodus pulcher Boulenger, 1887, from the western Amazon basin is designated as type-species of the new genus and redescribed.

 

Castro in 1999 mentioned this species as a Microglanis sp. on his comments on miniaturization and heterochrony.

 

 

 

Rhyacoglanis paranensis = dorsal view

 

Rhyacoglanis paranensis - dorsal view

 

 

Four new species are described: Rhyacoglanis annulatus, from the Río Orinoco basin, with a nearly ringed dark band on the caudal peduncle, and a larger distance between anus and anal-fin origin; R. epiblepsis, from the rio Madeira basin, with numerous dark spots scattered on the body, and rounded caudal-fin lobes; R. paranensis, from the upper rio Paraná basin, with three distinct dark bands on the body, and 31-33 total vertebrae; and R. seminiger, from the Rio Juruena basin, with subdorsal and subadipose dark bands fused anteroposteriorly, and a separate dark band on the caudal peduncle.

 

 

Characteristics

Body depressed from snout tip to dorsal-fin origin; progressively more compressed from that point to caudal-fin base. Dorsal profile of head and anterodorsal portion of body nearly straight from snout tip to dorsal-fin origin but slightly concave along occipital region. Dorsal-fin base nearly straight with slight posteroventral incline. Body profile nearly straight from end of dorsal-fin base to adipose-fin origin. Ventralprofile of head and body convex from lower jaw margin to end of anal-fin base, almost straight from anus to anal-fin origin. Caudal peduncle profile concave dorsally and ventrally.

Colour
Ground colour light brown in alcohol; light orange in life. Head with dark spots on dorsal surface, opercle, and region ventral to orbit. Region over adductor mandibulae muscle lightly coloured. Iris dark in alcohol; light gray in life. Dark subdorsal band with irregular anterior and posterior margins; extending to ventral region of body but not contacting contralateral counterpart. Subadipose band with irregular anterior and nearly straight posterior margins. Lightly colored region between subdorsal and subadipose bands with scattered dark spots. Anterior margin of caudal-peduncle band nearly straight and posterior margin in shape of shallow, posteriorly open sideways V. Dorsal fin with dark pigmentation covering fin other than for distal one-fifth. Adipose fin with dark blotch centrally. Anal fin with dark basal spot and dark stripe on midsection; two regions conjoined posteriorly. Caudal fin hyaline basally with broad dark band across each lobe and lobe tips largely hyaline. Pectoral and pelvic fins hyaline except for transverse dark stripe on each.

Aquarium Care

Provide plenty of hiding places to hide during the day and best kept in a small group of 2-3. Very secretive in its surroundings.

 

Compatibility

A good addition to the medium sized community tank, and will not harm the occupants unless they are small enough to fit into its mouth such as newly born fry and young fish.

 

Breeding

Not reported

Sexual Differences

Not recorded but usually the females are more rotund.

 

Diet

No problem with eating all types of aquarium fare, flake, tablets, pellets, live and frozen foods.


Glossary of Terms

Occipital: A median bone on the upper surface of the back of the head; pertaining to the occiput.

Dorsal fin: The primary rayed fin(s) on top of the body.
Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.

Hyaline:Transparent or clear without pigment..
Adipose fin: Fleshy finlike projection without rays, behind the rayed dorsal fin.
Caudal fin: The tail.
Caudal peduncle
: The narrow part of a fish's body to which the caudal or tail fin is attached.


Etymology

Rhyacoglanis: From the Greek rhyax = torrent + glanis = catfish; indicating a catfish inhabiting running waters in reference to the habitat of the genus. Gender masculine.
paranensis: The specific name, paranensis, is an adjective in reference to the occurrence of the species in the upper Rio Paraná basin.

References

Shibatta, Oscar Akio, & Vari, Richard P. (2017). A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotropical Ichthyology, 15(2), e160132. Epub June 30, 2017.https://dx.doi.org/10.1590/1982-0224-20160132
David Sands; pers. comm.


Photo Credits

© David Sands - From the publication: Catfishes of the World Vol. 3. Page 64/65.

 
Factsheet 253

Synonyms:
None
Common Name:
None
Family:
Pseudopimelodidae
Subfamily:
Pimelodoidea
Distribution:
South America: from the upper Rio Paraná basin, Brazil
Size: 
6.5cm. (2¾ins)
Temp:
24-28°C (75-83°F)
pH.:
6.5 - 7.5.
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