Phreatobius cisternarum

Goeldi 1905

Phreatobius cisternarum
Redrawn by Rhian Kendall from Reichel (1927)


Heptapterus cisternarum  (Goeldi, 1905) Buckup 1988




Syntypes: MHNG 1213.97 (labelled "TYP?", Buckup, 1988), MHNG 1505.91 (65 slide preparations), FMNH 58580 (ex CM 7603). This species is the type species by monotypy of the genus Phreatobius. This set of specimens includes the two individuals collected by Goeldi in 1903 plus a further four discovered two years later at the same site by Miranda. All six were given to Fuhrmann who later gave one (now FMNH 58580) to Eigenmann. Three of the remaining five were made into slide preparations (now MHNF 1505.91), one preserved in alcohol (now MHNG 1213.97) and the last (now lost) preserved in tetralin. It is no longer possible to determine which two were used by Goeldi in the original description (Mahnert 1976:475).


Type locality: A cistern (= well) at an unknown location on the Ilha de Marajó, Pará,  Brazil (Goeldi 1905). Recorded also from Belém city, Para (discovered there in 1963 by R. Arle (Thines and Proudlove 1986:732)) and Macapa city, Amapa to the south and north of Marajo respectively and 320 km apart.(Carvalho 1967,Trajano 1997). The distribution of this species appears to be restricted to an area in the mouth of the Amazon but is not known in detail (01oS, 50oW). A specimen collected in 1984 came from a well in Ananindeua, Pará (Mario de Pinna, pers. comm.).


The true habitat of this species is not known but it seems to be an inhabitant of underground water sheets around the mouth of the Amazon. All of the specimens so far collected were caught accidentally during the excavation of wells (Mario de Pinna pers. comm.).



The relationships of this interesting fish have been subject to debate since its description. In the original description Goeldi (1905) suggested that: "In total several features indicate that the fish belongs partly to the Trichomycteridae and partly to the Cetopsidae. Still other features are dominant enough to indicate an isolated position between these two groups". Fuhrmann (1905, 1905) disagreed and placed it amongst the Clariidae. Eigenmann (1918) stated that the species was a member of the subfamily Pimelodinae, and therefore the Heptapteridae, and that it was related to Heptapterus. Norman (1926) suggested that the relationships were uncertain. After a monumental anatomical study Reichel (1927) placed Phreatobius in the Siluridae but decided that it was sufficiently different from other members of this family to merit its own subfamily, the Phreatobiinae. Myers (1944) retained the subfamilial status but considered it to reside within the Trichomycteridae. Myers and Weitzman (1966) stated that the species “is different from the Trichomycteridae in lacking a nasal barb” and that it was included in the Trichomycteridae “only on general appearance”. Chardon (1968) examined many siluriform fishes and after considering all of the evidence in front of him replaced Phreatobius into the Heptapteridae. Thines (1955, 1969) returned it in the Trichomycteridae. Carvalho (1967) followed Eigenmann (1918) in pacing the species in the Pygidiidae but within the monotypic subfamily Phreatobiinae. More recently Buckup (1988) has suggested that Phreatobius cisternarum be placed in the genus Heptapterus as it shares an anal fin ray count of 16 or more with other species in this genus. This action has not been wholly accepted and has not been adopted here. The most recent contribution is from Lundberg, Bornbusch and Mago‑Leccia (1991) who place the animal in the subfamily Rhamdiinae of the Heptapteridae.

Until the 1980s the genus Phreatobius was monotypic but there are now at least two further species which live in leaf litter in acidic blackwater tributaries of the Amazon (Henderson 1990 Trajano 1997d). De Pinna (1998) postulates a relationship between Phreatobius and Horaglanis based on similar skull morphology. A recent photograph of Horaglanis krishnai shows that it is blood red in colour, a very rare condition for fishes (De Pinna 1998), as is Phreatobius and this may be a synapomorphy for a group containing the two genera. Clearly there is much to be learned about the exact systematic position of this interesting animal.

Conservation Status

MuG [LC:3.1:2011]

(World Conservation Monitoring Centre. 1996. Phreatobius cisternarum. The IUCN Red List of Threatened Species 1996: Downloaded on 07 July 2017).

The habitat of this animal is such that very few specimens are known and only one was discovered during the 1980s

Museum Holdings

As above plus: MZUSP 28309 (Lundberg, Bornbusch and Mago‑Leccia 1991), MNRJ 11569 (De Pinna 1998).

Key References

Goeldi, E. Journal Article 1905 Nova zoologica aus der Amazonas-Region. Neue Wirbeltiere
Fuhrmann, O. Journal Article 1905 Scleropages formosum und uber Phreatobius cisternarum
Fuhrmann, O. Journal Article 1905 Scleropages formosum und uber Phreatobius cisterarum
Eigenmann, C. H. Journal Article 1918 The Pygidiidae, a family of South American catfishes
Eigenmann, C. H. Journal Article 1919 Trogloglanis pattersoni, a new blind fish from San Antonio, Texas
Reichel, M. Journal Article 1927 Etude anatomique du Phreatobius cisternarum Goeldi, Silure aveugle du Bresil
Myers, G. S. Journal Article 1944 Two extraordinary new blind nematognath fishes from the Rio Negro, representing a new subfamily of Pygidiidae, with a rearrangement of the genera of the family
Gosline, W. A. Journal Article 1945 Catalogo dos nematognathos de agua-doce da America do Sol e Central
Fowler, H.W. Journal Article 1954 Os peixes de agua doce do Brasil. Vol. 2
DeCarvalho, A.L. Book Section 1967 Novas dados para o conhecimento de Phreatobius cisternarum Goeldi (Pisces, Pygidiidae, Phreatobiinae)
Chardon, M. Journal Article 1968 Anatomie comparee de l'appareil de Weber et des structures connexes chez les Siluriformes
Thines, G. and Proudlove, G. S. Book Section 1986 Pisces
Buckup, P. A. Journal Article 1988 The genus Heptapterus (Teleostei, Pimelodidae) in southern Brazil and Uruguay, with the description of a new species
Henderson, P. A. Journal Article 1990 Fish of the Amazonian Igapo: stability and conservation in a high diversity-low biomass system
Lundberg, J. G., Bornbusch, A.H. and Mago-Leccia, F. Journal Article 1991 Gladioglanis conquistador n.sp. from Ecuador with diagnoses of the subfamilies Rhamdiinae Bleeker and Pseudopimelodinae n. subf. (Siluriformes: Pimelodidae)
Trajano, E Journal Article 1997 Food and reproduction of Trichomycterus itacarambiensis, a cave catfish from south-eastern Brazil
Bockmann, F.A. and Guazzelli, G.M. Book Section 2003 Family Heptapteridae (Heptapterids)
Ohara, W.M., Da Costa, I.D. and Fonseca, M.L. Journal Article 2016 Behavioiur, feeding habits and ecology of the blind catfish Phreatobius sanguijuela (Ostariophysi: Siluriformes)
Liu, A. Schneider, P. and Taylor,J. Conference Paper 2019 Opsins in the dark. Characterising light sensitive genes in the Brazilian eyeless cavefish Phreatobius cisternrum