Ancistrus formoso

Sabino and Trajano 1997

Ancistrus formoso
Drawing by Rhian Kendall from photograph in Sabino and Trajano (1997)






Holotype: MZUSP 51836 72.8mm SL. Paratype MZUSP (?) no number 79mm SL.


Type locality: Buraco do Ducho cave, Serra da Bodoquena, Municipio de Bonito, Mato Grosso do Sul, Brazil (21o8’S, 56o28’W). Collected also from the Formosinho Resurgence in the same area. These caves are hydrologically related. Known also from N, Rio Formoso on the Formoso River drainage (Cordeiro, Borghezan and Trajano 2014).


This species lives in flooded caves forming the Formoso system. These caves belong to the Paraguai River basin and are accessible only by diving to depths of up to 120m. Troglomorphic fishes are found between 15m and 40m depth but are commonest below 30m. The phreatic passages inhabited by these fishes have smooth walls with few refugia and the fishes are seen on the walls. Potential predators, e.g. Rhamdia quelen (Heptapterinae) and Hoplerythrinus unitaeniatus (Erythrinidae) may reach depth of up to 45m but most are restricted to the twilight zone where A. formoso is not usually seen (Bessa and Trajano 2001, 2002).


This species is highly stygomorphic. Individuals are totally anophthalmic and depigmented. One specimen was a true albino (see Trajano and De Pinna 1996 for a discussion of depigmentation and albinism). The high degree of stygomorphism suggests that this species has been isolated in the subterranean habitat for a long period (Bessa and Trajano 2002).

Conservation Status

[NE] [VU D2:3.1:2011]

Ancistrus formoso is endemic to Brazil, known only from the caves system of the Formoso River, MS, located outside the Bodoquena National Park. The area of occupation is less than 10 km2. Limestone mining for cement production is expanding in the region, setting itself up as a potential future plausible threat. Protecting the cave system from the surroundings of the Parna da Bodoquena is essential for the conservation of the species, through the expansion of Parna or the creation of some conservation unit. The species is classified as Vulnerable (VU) under criterion D2. [Google Translate]

Museum Holdings

As above only.

Internet Resources

Web page for the Family Loricariidae

Key References

Sabino, J. and Trajano, E. Journal Article 1997 A new species of blind armoured catfish, genus Ancistrus, from caves of Bodoquena region, Mato Grosso do Sul, southwestern Brazil (Siluriformes, Loricariidae, Ancistrinae)
Trajano, E. and Gerhard, P. Journal Article 1997 Light reaction in Brazilian cave fishes (Siluriformes: Pimelodidae, Trichomycteridae, Loricariidae)
Bessa, E. and Trajano, E. Conference Proceedings 2001 Light reaction and cryptobiotic habits in two cave-dwelling Brazilian armoured catfishes, genus Ancistrus (Siluriformes: Loricariidae)
Bessa, E. and Trajano, E. Journal Article 2001 Light recation and cryptobiotic habitats in armoured catfishes, genus Ancistrus, from caves in central and north-eastern Brazil
Armbruster, J.W. Journal Article 2004 Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae
Felice, V., Visconti, M.A. and Trajano, E. Journal Article 2008 Mechanisms of pigmentation loss in subterranean fishes
Cordeiro, L.M., Borghezan, R. and Trajano, E. Journal Article 2014 Subterranean biodiversity in the Serra da Bodoquena karst area, Paraguay river basin, Mato Grosso do Sul, Southwestern Brazil
Trajano, E, Gallao, J.E and Bichuette, M. E. Journal Article 2016 Spots of high biodiversity of troglobites in Brazil: the challenge of measuring subterranean diversity
Gallão, J.E. and Bichuette M.E. Journal Article 2018 Brazilian obligatory subterranean fauna and threats to the hypogean environment
Splendore de Borba, R., Mariotto, S., Centofante, L., Zawadzki C.H. and Parise-Maltempi, P.P. Journal Article 2019 Molecular discrimination of Ancistrus lineages (Siluriformes: Loricariidae) using barcode DNA tool
Mendes, I.S., Prosdocimi, F., Schomaker-Bastos, A., Furtado, C., Ferreira, R.L., .Pompeu, P.S. and Carvalho, D.C. Journal Article 2019 On the evolutionary origin of Neotropical cavefish Ancistrus cryptophthalmus (Siluriformes, Loricariidae) based on the mitogenome and genetic structure of cave and surface populations