New research has finally shed light on the age old question of how many valid species of catfishes there are in the world.
According to Carl Ferraris, who published a comprehensive checklist of the fossil and living catfishes in a recent issue of the journal Zootaxa, there are 3093 valid species in 478 genera (out of 4624 proposed species names and 810 proposed generic names) and 36 families as of 2005.
Of these 3093 valid species, 72 species in 19 genera are known exclusively from fossil remains.
The checklist provides nomenclatural data (author, source of original description, type locality, details of the name-bearing type) for each valid species, and also names a new akysid catfish genus, Pseudobagarius, for the Akysis pseudobagarius group.
Pseudobagarius is diagnosed as "Akysidae with the following combination of characters: snout extending well anterior of margin of lower jaw, rendering mouth subterminal; narial openings relatively large and closely set; and caudal fin deeply forked."
Not surprisingly, the largest catfish family is the Loricariidae, with 716 valid species in 96 genera.
The smallest family is the recently described Lacantuniidae, with only a single valid species.
Three genera of living catfishes could not be assigned to existing catfish families: Conorhynchos and Phreatobius from South America, and Horabagrus from Asia.
For more information, see the paper: Ferraris, CJ Jr. (2007) Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418: 1"628.