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Environmental disasters affecting Brazilian rivers have been frequent recently, especially involving mining activities. Two recent dam-rupture events suddenly released millions of cubic meters of iron tailings downstream into two major Brazilian watersheds. These events generated major losses to the environment and human life. Additionally, the biodiversity in both watersheds was still incompletely known. Two new species of the armoured catfish genus Hypostomus were discovered in the Rio Paraopeba and surrounding rivers of the Rio São Francisco Basin. The species share some main characteristics including a depressed body, large dark spots on a clearer background and the absence of keels on flanks. However, while one species (Hypostomus freirei sp. n.) has a large mandibular ramus and numerous slender teeth, the other (Hypostomus guajupia sp. n.) has a shorter mandibular ramus and few robust teeth. The discovery of these two new mid-sized fish species emphasizes the presumption that the effects of major environmental disasters cannot be fully estimated as local biodiversity is not completely known. This discovery in a recently devastated area also shows that tough environmental laws for the protection, supervision and mitigation of major impacts are urgently needed in developing countries.

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Characidium cacah, new species, apparently endemic to the rio das Velhas sub-basin, upper rio São Francisco basin, Brazil, is described. The new species is easily distinguished from congeners, except C. chicoi, C. helmeri, C. mirim, C. nana, C. nupelia, C. stigmosum and C. xavante, by having an incomplete lateral line and for lacking an adipose fin. The new species can be diagnosed from the aforementioned species by a series of characters, including the presence of 12 circumpeduncular scales, the isthmus completely scaled, a thin inconspicuous or dashed midlateral dark stripe, the absence of a conspicuous peduncular blotch, and humeral blotch and basicaudal spot variably marked.

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A new species of Hyphessobrycon is described from a marshland area in the headwaters of Rio Jequitinhonha basin, Minas Gerais, Brazil. The new species differs from congeners by presenting a single well-delimited conspicuous humeral blotch, rounded to vertically oval, restricted to the area dorsal to the lateral-line row of scales, without a narrower downward extension, greatest body depth anterior to dorsal-fin origin, bony processes in anal and pectoral-fin rays of males and four teeth in the inner row of the premaxillary bone. The new species presents a set of morphological features shared by some species currently assigned to Hasemania, Myxiops and to the Astyanax scabripinnis complex. Some of these features are discussed.

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A new species of Trichomycterus is described from rocky and psammic sectors near the main channel of the middle and upper Rio Doce basin in Southeastern Brazil. Trichomycterus astromycterus n. sp., is distinguished from all congeners by a number of autapomorphic characters, such as the distally expanded maxilla; the short and thick mesethmoid cornua; and the elongated anterior process of the vomer. Additional characters (short barbels, large head, 33 vertebrae, ii+8 or ii+9 dorsal-fin rays, nine dorsal-fin pterygiophores, markedly enlarged lips, narrow caudal peduncle, bilobed caudal fin with the lower lobe longer than the upper one) also distinguish the new species from all its congeners in Southeastern Brazil and from most congeners anywhere. Examination of internal anatomy reveals that T. astromycterus shares some intriguing characteristics with the austral genus Bullockia Arratia et al., 1978. However, the phylogenetic significance of such similarities is still uncertain and will require further comparative study. For this reason, the new species is provisionally included in the all-encompassing genus Trichomycterus. An osteological description is presented on the basis of CT-scan imaging and cleared and stained specimens.

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Sarcoglanidinae and Glanapteryginae catfishes are among the most unusual elements of the Neotropical freshwater fish fauna. Microcambeva ribeirae, M. barbata and M. draco are miniaturized Sarcoglanidinae known to occur in sandy microhabitats in drainages of the Brazilian Atlantic Forest. Due to their specific habitats, specimens of Microcambeva are rare in fish collections, and new records are considered noteworthy to warrant report. Recently, specimens of this genus were newly found in the Rio Doce basin in Minas Gerais and Espírito Santo States. Such new records expand the known geographic distribution of Microcambeva. Further records of Microcambeva for Rio Peruípe in south Bahia State are also reported. Comments on the distribution of Microcambeva species along the Atlantic Forest coastal basins and suggestions on its conservation status are also offered.

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A new species of the loricariid genus Pareiorhaphis is described based on specimens from several tributaries of the upper and middle rio Jequitinhonha basin, Minas Gerais State, eastern Brazil. The new species increases the number of known species of Pareiorhaphis to 25 and, at the same time, represents the second member of the subfamily Neoplecostominae reported from the rio Jequitinhonha basin. The new species is diagnosed from all remaining congeners by a putative autapomorphic feature related to the color pattern: a well-defined, dark brown stripe on the median series of lateral plates that extends along the flank from the posterior margin of compound pterotic to the caudal-fin base. The shallow caudal peduncle and the comparatively larger number of dentary teeth also distinguish the new species from most congeners. The new species is also compared to Pareiorhaphis stephanus, a syntopic congener with similar traits.(AU)

Uma nova espécie de loricariídeo do gênero Pareiorhaphis é descrita com base em espécimes coletados em vários tributários da parte superior e média da bacia do rio Jequitinhonha, no estado de Minas Gerais, leste do Brasil. A nova espécie eleva para 25 o número de espécies conhecidas de Pareiorhaphis e ao mesmo tempo representa o segundo registro de um membro de Neoplecostominae na bacia do rio Jequitinhonha. A nova espécie é diagnosticada de todas as demais congêneres por uma característica até então única relacionada ao padrão de colorido, uma faixa marrom escura bem definida na série média de placas laterais, que se estende ao longo do flanco, desde a margem posterior do pterótico composto até a base dos raios médios da nadadeira caudal. O pedúnculo caudal baixo e o número de dentes comparativamente alto no dentário, também distinguem a nova espécie da maioria das demais congêneres. A nova espécie é comparada com Pareiorhaphis stephanus, uma congênere sintópica com caracteres similares.(AU)

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RESUMEN

A new species of the loricariid genus Pareiorhaphis is described based on specimens from several tributaries of the upper and middle rio Jequitinhonha basin, Minas Gerais State, eastern Brazil. The new species increases the number of known species of Pareiorhaphis to 25 and, at the same time, represents the second member of the subfamily Neoplecostominae reported from the rio Jequitinhonha basin. The new species is diagnosed from all remaining congeners by a putative autapomorphic feature related to the color pattern: a well-defined, dark brown stripe on the median series of lateral plates that extends along the flank from the posterior margin of compound pterotic to the caudal-fin base. The shallow caudal peduncle and the comparatively larger number of dentary teeth also distinguish the new species from most congeners. The new species is also compared to Pareiorhaphis stephanus, a syntopic congener with similar traits.(AU)

Uma nova espécie de loricariídeo do gênero Pareiorhaphis é descrita com base em espécimes coletados em vários tributários da parte superior e média da bacia do rio Jequitinhonha, no estado de Minas Gerais, leste do Brasil. A nova espécie eleva para 25 o número de espécies conhecidas de Pareiorhaphis e ao mesmo tempo representa o segundo registro de um membro de Neoplecostominae na bacia do rio Jequitinhonha. A nova espécie é diagnosticada de todas as demais congêneres por uma característica até então única relacionada ao padrão de colorido, uma faixa marrom escura bem definida na série média de placas laterais, que se estende ao longo do flanco, desde a margem posterior do pterótico composto até a base dos raios médios da nadadeira caudal. O pedúnculo caudal baixo e o número de dentes comparativamente alto no dentário, também distinguem a nova espécie da maioria das demais congêneres. A nova espécie é comparada com Pareiorhaphis stephanus, uma congênere sintópica com caracteres similares.(AU)

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The digestive tract of Trachelyopterus striatulus (Steindachner, 1877) was studied using morphological, histological, and histochemical techniques. The barbels, lips and tongue had stratified squamous epithelium with mucous, claviform cells, and taste buds. Trachelyopterus striatulus had a dental plaque with villiform teeth. The bucopharyngeal cavity was formed by the gill apparatus and pharyngeal teeth with vilifform denticles. The oesophagus presented stratified squamous epithelium with mucous cells and taste buds. The stomach included cardiac, fundic, and pyloric regions and a simple prismatic epithelium with prismatic cells that reacted positively to periodic acid-Schiff (PAS) and amylase+PAS. Only the cardiac and pyloric regions responded positively to alcian blue pH 2.5 (Ab pH 2.5) and alcian blue pH 0.5 (Ab pH 0.5). The cardiac and fundic regions exhibited tubular gastric glands. The intestine was 118.90 ± 22.49 mm long with an intestinal coefficient (CO) of 0.83 ± 0.13. The epithelium was simple prismatic with a brush border and goblet cells, and a greater number of goblet cells were found in the caudal region of the intestine. The mucous cells and goblet cells reacted positively to PAS, amylase+PAS, Ab pH 2.5, and Ab pH 0.5. We analysed if the function of the mucosubstances and morphological characteristics of the digestive tract of T. striatulus are compatible with omnivorous feeding habit.

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The digestive tract of Trachelyopterus striatulus (Steindachner, 1877) was studied using morphological, histological, and histochemical techniques. The barbels, lips and tongue had stratified squamous epithelium with mucous, claviform cells, and taste buds. Trachelyopterus striatulus had a dental plaque with villiform teeth. The bucopharyngeal cavity was formed by the gill apparatus and pharyngeal teeth with vilifform denticles. The oesophagus presented stratified squamous epithelium with mucous cells and taste buds. The stomach included cardiac, fundic, and pyloric regions and a simple prismatic epithelium with prismatic cells that reacted positively to periodic acid-Schiff (PAS) and amylase+PAS. Only the cardiac and pyloric regions responded positively to alcian blue pH 2.5 (Ab pH 2.5) and alcian blue pH 0.5 (Ab pH 0.5). The cardiac and fundic regions exhibited tubular gastric glands. The intestine was 118.90 ± 22.49 mm long with an intestinal coefficient (CO) of 0.83 ± 0.13. The epithelium was simple prismatic with a brush border and goblet cells, and a greater number of goblet cells were found in the caudal region of the intestine. The mucous cells and goblet cells reacted positively to PAS, amylase+PAS, Ab pH 2.5, and Ab pH 0.5. We analysed if the function of the mucosubstances and morphological characteristics of the digestive tract of T. striatulus are compatible with omnivorous feeding habit.(AU)

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