The genus Brycon Mller amp; Troschel (Ostariophysi: Characiformes: Bryconidae) of Esprito Santo State, Brazil: new records and comments on conservation.

The occurrence of the species of the genus Brycon (Characiformes: Bryconidae) in Esprito Santo State is herein reviewed. Brycon opalinus, a species formerly known only from the upper rio Paraba do Sul and upper rio Doce basins, is recorded for the first time in the rio Itapemirim, an independent coastal basin in southern Esprito Santo State, Brazil. With the records of B. opalinus, four Brycon species are now known from Esprito Santo State: B. insignis in the rio Itabapoana basin, on the boundary between Rio de Janeiro and Esprito Santo, B. opalinus in the rio Itapemirim basin, B. dulcis in the rio Doce basin, and B. ferox in the rio Barra Seca, rio Itanas and the rio So Mateus basins. Additionally worth highlighting is that several fisherman and local inhabitants report the occurrence Brycon vermelha in the rio Cotax, a tributary of the rio So Mateus in Esprito Santo and Minas Gerais states, although there are no preserved specimens of B. vermelha from river basins other than the rio Mucuri, in Minas Gerais state.

A multiple hypothesis approach to explain species richness patterns in neotropical stream-dweller fish communities.

Several hypotheses are used to explain species richness patterns. Some of them (e.g. species-area, species-energy, environment-energy, water-energy, terrestrial primary productivity, environmental spatial heterogeneity, and climatic heterogeneity) are known to explain species richness patterns of terrestrial organisms, especially when they are combined. For aquatic organisms, however, it is unclear if these hypotheses can be useful to explain for these purposes. Therefore, we used a selection model approach to assess the predictive capacity of such hypotheses, and to determine which of them (combined or not) would be the most appropriate to explain the fish species distribution in small Brazilian streams. We perform the Akaike's information criteria for models selections and the eigenvector analysis to control the special autocorrelation. The spatial structure was equal to 0.453, Moran's I, and require 11 spatial filters. All models were significant and had adjustments ranging from 0.370 to 0.416 with strong spatial component (ranging from 0.226 to 0.369) and low adjustments for environmental data (ranging from 0.001 to 0.119) We obtained two groups of hypothesis are able to explain the richness pattern (1) water-energy, temporal productivity-heterogeneity (AIC = 4498.800) and (2) water-energy, temporal productivity-heterogeneity and area (AIC = 4500.400). We conclude that the fish richness patterns in small Brazilian streams are better explained by a combination of Water-Energy + Productivity + Temporal Heterogeneity hypotheses and not by just one.

Morphology of the epidermis of the neotropical catfish Pimelodella lateristriga (Lichtenstein, 1823) with emphasis in club cells.

The epidermis of Ostariophysi fish is composed of 4 main cell types: epidermal cells (or filament containing cells), mucous cells, granular cells and club cells. The morphological analysis of the epidermis of the catfish Pimelodella lateristriga revealed the presence of only two types of cells: epidermal and club cells. The latter were evident in the middle layer of the epidermis, being the largest cells within the epithelium. Few organelles were located in the perinuclear region, while the rest of the cytoplasm was filled with a non-vesicular fibrillar substance. Club cells contained two irregular nuclei with evident nucleoli and high compacted peripheral chromatin. Histochemical analysis detected prevalence of protein within the cytoplasm other than carbohydrates, which were absent. These characteristics are similar to those described to most Ostariophysi studied so far. On the other hand, the epidermal cells differ from what is found in the literature. The present study described three distinct types, as follows: superficial, abundant and dense cells. Differences among them were restricted to their cytoplasm and nucleus morphology. Mucous cells were found in all Ostariophysi studied so far, although they were absent in P. lateristriga, along with granular cells, also typical of other catfish epidermis. The preset study corroborates the observations on club cells' morphology in Siluriformes specimens, and shows important differences in epidermis composition and cell structure of P. lateristriga regarding the literature data.