Phreatobius

Phreatobius
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	incertae sedis
Genus:	Phreatobius Goeldi, 1905
Type species
Phreatobius cisternarum Goeldi, 1905

Phreatobius is a genus of catfishes (order Siluriformes) from South America.

For quite some time Phreatobius cisternarum was the only species in the genus. However, two new species were described relatively recently in 2007, Phreatobius dracunculus and Phreatobius sanguijuela.

Phreatobius has been classified with a number of different families: Clariidae, Plotosidae, Trichomycteridae, Cetopsidae, and Pimelodidae. Most recently, it has been classified in Heptapteridae. Its phylogenetic position remains uncertain. The family placement of the genus has remained problematic and thus it is not classified in any of the existing families, though Fishbase treats it as a member of Heptapteridae.

An undescribed species of Phreatobius lives in leaf litter.Phreatobius walkeri, a nomen nudum, is provided by the Guinness Book of World Records, to describe this fish that stays on land for extended periods of time. Two additional quite distinctive species of Phreatobius, as yet undescribed, are known from the Río Negro of Brazil.

There are currently three recognized species in this genus:

Phreatobius species all live underground and are known only from artificial wells penetrating near-surface aquifers of the Amazon basin. The genus has one of the widest distribution of any hypogean fish genus, with P. sanguijuela from the upper Amazon, some 2000 km from reported locations of P. cisternarum near the Amazon River mouth, and P. dracunculus also approximately 1900 km from the Rio Branco drainage area.

...
Wikipedia