Aphanotorulus
Aphanotorulus is a genus of armored catfishes native to the Amazon, Orinoco, Essequibo and Jaguaribe basins in South America. They typically occur on a sand or gravel bottom in slow to moderately flowing rivers and streams, but some species occur in areas with fast current. The largest species in the genus reaches up to  in standard length.

Taxonomy
The taxonomy of this genus has been a matter of dispute, all having been placed in Hypostomus in the past, and some occasionally placed in Squaliforma. Squaliforma is now regarded as a synonym of Aphanotorulus, but species west of the Andes have been moved to Isorineloricaria.

There are currently 7 recognized species of Aphanotorulus:

 Aphanotorulus ammophilus Armbruster & Page, 1996
 Aphanotorulus emarginatus (Valenciennes, 1840)
 Aphanotorulus gomesi (Fowler, 1941)
 Aphanotorulus horridus (Kner, 1854)
 Aphanotorulus phrixosoma (Fowler, 1940)
 Aphanotorulus rubrocauda Oliveira, Py-Daniel & Zawadzki, 2017
 Aphanotorulus unicolor (Steindachner, 1908)

Of these species, the validity of A. phrixosoma is questionable, as the only known specimen likely is a hybrid between A. horridus and A. unicolor.

References

Hypostominae
Fish of South America
Catfish genera
Taxa named by Isaäc J. H. Isbrücker
Taxa named by Han Nijssen
Freshwater fish genera