Abstract
A taxonomic review of Spectracanthicus Nijssen & Isbrücker, including Oligancistrus Rapp Py-Daniel, following a phylogenetic study, is presented. Additionally to S. punctatissimus(Steindachner) and S. murinus Nijssen & Isbrücker, three new species are recognized based on the examination of 159 specimens: S. immaculatus n. sp. from rio Tapajós basin, differs from its congeners by its color pattern consisting of a dark gray body, with no dots or spots, and by having very slender teeth; Spectracanthicus tocantinensisn. sp., from the rio Tocantins drainage is distinguished by the color pattern consisting of dark brown or black body with small, yellowish dots (except in S. punctatissimus), presence of thick teeth, infraorbital 4 forming most of the posterior edge of the orbit and the large basipterigium fenestrae; and Spectracanthicus zuanonin. sp., from the rio Xingu basin is diagnosed by its color pattern consisting of large, white spots and by the larger orbital diameter. Other characters based on osteological features are also usefull to distinguish the species. A key to the species of the genus and a brief discussion of their threats and conservation are also provided.
Highlights
The Loricariidae is the largest family within Siluriformes and includes more than 750 species, which represent about 25% of the diversity of catfishes (Reis et al, 2003; Ferraris, 2007)
The Ancistrini is not diagnosed by a unique characters (Armbruster, 2004), most of its genera are readily recognized by having the opercle modified into a rectangular bar- or sickle-shaped structure with associated eversible plates supporting hypertrophied odontodes
This character is apparently reversed in some taxa, and the opercle has triangular or oval shaped, which is the plesiomorphic state within Hypostominae (i.e., Spectracanthicus and Hypostomus)
Summary
The Loricariidae is the largest family within Siluriformes and includes more than 750 species, which represent about 25% of the diversity of catfishes (Reis et al, 2003; Ferraris, 2007). The Ancistrini is not diagnosed by a unique characters (Armbruster, 2004), most of its genera are readily recognized by having the opercle modified into a rectangular bar- or sickle-shaped structure with associated eversible plates supporting hypertrophied odontodes. This character is apparently reversed in some taxa, and the opercle has triangular or oval shaped, which is the plesiomorphic state within Hypostominae (i.e., Spectracanthicus and Hypostomus). A brief phylogenetic discussion on the relationships and a key to the species of the genus are provided
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