Delturinae is a subfamily of catfish

Catfish

Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

es (order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Siluriformes) of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Loricariidae

Loricariidae

Loricariidae is the largest family of catfish , with almost 700 species and new species being described each year. Loricariids originate from fresh water habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and...

. It includes two genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, Delturus and Hemipsilichthys

Hemipsilichthys

Hemipsilichthys is a genus of catfishes belonging to the family Loricariidae. These wide-mouthed freshwater catfishes are all restricted to Brazil, mostly in the coastal basins of the south and southeast with one species, Hemipsilichthys regani, further north in the Amazon basin...

. This group is sister

Cladistics

Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 to all other loricariids except Lithogenes

Lithogenes

Lithogenes is a genus of catfish of the family Loricariidae. It is the only genus within the subfamily Lithogeneinae. This genus contains two species: L. villosus, the type species, and L. valencia, a possibly extinct species.-Taxonomy:L. villosus was described in 1909 by Carl H. Eigenmann. L...

. The geographical distribution of Delturinae, exclusively on the south-eastern Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

ian Shield, indicates that south-eastern Brazil acts as either a refugium for basal loricariid taxa or a point of origin for the Loricariidae.

Both genera can be separated from all other loricariids by the presence of a postdorsal ridge made up of raised, median, unpaired plates and the presence of an adipose fin membrane. Hemipsilichthys can be separated from Delturus by not having the anterior plates of the ridge contacting the lateral plates (juvenile Delturus also have this condition) and by having a rectangular (vs. V-shaped) spinelet.