Optimal foraging of Neotropical otters (Carnivora: Mustelidae) in an urban river and predominance of generalist and sedentary fish in their diet

Lontra longicaudis Olfers, 1818 is a semi-aquatic carnivore widely distributed in the Neotropical region. Understanding their diet contributes to an indirect understanding of their ecology and the composition of the local fauna. To this end, we analyzed 109 fecal samples and identified 238 morphological structures; these samples were collected between May 2006 and September 2007 from the Santa Lúcia Biological Station (SLBS) in southeastern Brazil. The area is intersected by the Timbuí River, which arrives at the site after crossing the urban perimeter of the city of Santa Teresa in the state of Espírito Santo. We found a predominance of fish in the otters' diets (82%), mainly cichlids (50%), which are fish with sedentary habits and low mobility levels. The crustacean Trichodactylus fluviatilis Latreille, 1828 was the third most consumed taxon; this occurred mainly during the rainy season, corresponding to the crustacean's reproductive period, when it is more vulnerable to predation. Otters exhibited a seasonal variation in their prey selectivity. Furthermore, they displayed opportunistic foraging behavior, as the most preyed fish were those with both low mobility and a high frequency in the environment, followed by fish with high mobility and high frequency, and then those with low mobility and low frequency. We concluded that the feeding habits of the otters in the SLBS are in line with the optimal foraging theory since prey selection was optimized through the balance between net energy gained and the energy costs of foraging.

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.

Contribuição ao conhecimento da ictiofauna da Bacia do Alto Rio Iguaçu, Paraná, Brasil / Contribution to the knowledge of the ichthyofauna from the upper Iguaçu River Basin, Paraná, Brazil / Contribución al Conocimiento de la Fauna de Peces de la Cuenca Hidrográfica del Alto Rio Iguaçu, Paraná, Brasil

Com base no material depositado no Museu de História Natural Capão da Imbuia é apresentado um levantamento atualizado da ictiofauna da Bacia do Alto Rio Iguaçu. O presente estudo detectou a presença de 41 espécies, das quais oito são endêmicas e dez apresentam status taxonômico ainda não definido. Três espécies são apresentadas pela primeira vez para a Bacia do Rio Iguaçu (Astyanax sp. n., Misgurnus anguillicaudatus e Clarias gariepinus), sendo que M. anguillicaudatus é espécie exótica muito comum em aquarismo e C. gariepinus é uma espécie exótica utilizada na piscicultura regional. Astyanax altiparanae é citada pela primeira vez para o Alto Iguaçu. Durante o presente levantamento, a espécie considerada rara Glandulocauda melanopleura foi registrada, e Hyphessobrycon taurocephalus, conhecida somente através da série tipo, não foi encontrada. Uma chave para identificação das espécies do Alto Iguaçu é apresentada.(AU)

A survey of the species of fishes from the Upper Iguaçu River Basin deposited in Museu de História Natural Capão da Imbuia is presented. Forty-one species were identified, of wich eight are endemics and ten belong to indefinite taxonomic status. Three species (Astyanax sp. n., Misgurnus anquillicaudatus and Clarias gariepinus) are mentioned by the first time to be basin. Misgurnus anguillicaudatus is a very common exotic aqurian fish and Clarias gariepinu is also an exotic fish used in fish culture. Astyanax altiparanae is a new record for the Upper Iguaçu River Basin. During te present survey, Glandulocauda melanopleura, which was considered rare was registered, and Hyphessobrycon taurocephalus, know only by the type series, was not found. An identification key for all the species of fishes recorded is provided.(AU)

Un levantamiento de la ictiofauna del curso superior del Rio Iguaçu y una clave para la identificación de sus especies se presenta basado en material depositado en el Museu de História Natural Capão da Imbuia. Este estudio ha descubierto la presencia de 41 especies, siendo que ocho son endémicas y diez fueron consideradas con status taxonómicos indefinidos. Tres especies (Astyanax sp. n., Misgurnus anquillicaudatus y Clarias gariepinus) se mencionan por mrimera vez en esta cuenca hidrográfica, y se lo registra Astyanax altiparanae por primera vez para el alto curso del rio Iguaçu. M isgurnus anguillicaudatus y Claias gariepinus son peces exóticos muy comones en peceras filia y en la piscicultura, respectivamente. Durante el presente estudio, Glandulocauda melanopleura que era considerada rara fue registrada, y Hyphessobrycon taurocephalus, sólo conocida por la seria tipo, no fue encontrada.(AU)