Brazilian ichthyologists have revised the doradid catfish genus Hassar in the most recent issue of the journal Neotropical Ichtyology.
José Birindelli, Danielle Fayal and Wolmar Wosiacki recognize four species of the genus (sometimes known in the aquarium trade as mouse catfishes) in the study, of which one is described as a new species.
Hassar affinis
This species is known from northeastern Brazil, including the Turiaçu, Pindaré-Mearim, Itapecuru and Parnaíba river drainages. It differs from congeners in having a blackened tip of the dorsal fin, by the shape of the swim bladder, and the morphology of the midlateral bony scutes. Hassar woodi is its junior synonym.
Hassar gabiru
This species is distinguished from congeners by the shape of its swim bladder, the morphology of the midlateral bony scutes, and relatively deeper body. It is known from the middle to upper Xingu River drainage.
Hassar orestis
This species is known from the Orinoco, Essequibo and Amazon river drainages, excluding the Tocantins and middle to upper Xingu river drainages. It differs from congeners by the shape of its swim bladder, the morphology of the midlateral bony scutes, tip of the upper caudal-fin lobe usually darkened, and relatively more slender body. Hassar notospilus and H. ucayalensis are its junior synonyms.
Hassar wilderi
This species is distinguished from congeners by the shape of its swim bladder and the morphology of the midlateral bony scutes. It is known from the Tocantins and Araguaia river drainages. Hassar iheringi is its junior synonym.
According to the authors, all species of Hassar typically inhabit swift-flowing sections of rivers (usually the main channel) flowing over a substrate of fine sand.
For more information, see the paper: Birindelli, JLO, DF Fayal and WB Wosiacki (2011) Taxonomic revision of thorny catfish genus Hassar (Siluriformes: Doradidae). Neotropical Ichthyology 9, pp. 515–542.
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