Specimens of aeglid anomuran freshwater crabs (Anomura: Aeglidae) from Uruguay deposited in Uruguayan and Brazilian scientific collections included a new species of Aegla from the Pampa biome. This discovery is the first new species of this genus to be described from Uruguay since 1942, and raises the number of species of Aegla found in that country to four. The new species is described and illustrated, and a map of all Uruguayan species of this genus is provided.
We compared the effect of different diets in the biochemical composition, levels of lipoperoxidation and survival rates of males and females of Hyalella bonariensis. These crustaceans live in limnetic environments and different kinds of food habits are present in the genus Hyalella. Adult animals were collected in the spring (September) in a stream near to Salto city, Buenos Aires. In the laboratory, the animals were kept submerged in aquariums, separated by sex, under controlled conditions and survive rates were observed. They were fed ad libitum for 45 days with four different diets, and after this period the animals were used for biochemical determinations. Statistical analysis revealed significant differences in the responses to glycogen, proteins, lipids, triglycerides and lipoperoxidation levels in both sexes of these amphipods taken from the natural environment. Animals that received macrophytes associated a ration with high content of proteins (43%) during 45 days presented the major survival rates (males= 86.6% and females= 96.6%). These responses can be revealed that this specie primarily feeding macrophytes associated with deposit feeder, and that this diet is more generalized. This study showed the importance of the proteins in diet of this amphipod, were the females increased the reserves of proteins and triglycerides with different diets probably for reproductive events and male increased the reserves of glycogen and triglycerides for reproductive events and growth.
Two new freshwater species of amphipods from Brazil are described here. Hyalella xakriaba n. sp. occurs in the hydrographic basin of the São Francisco River, in a biome characterized by a semiarid climate, in the state of Minas Gerais. This new species constitutes the northernmost record of the genus in Brazil. Hyalella kaingang n. sp. occurs in the hydrographic basin of the Mampituba River, located in Rio Grande do Sul, the southernmost state in Brazil. Currently 14 species of Hyalella are known in Brazil, cave species among them. Some morphological characters and their respective states are analyzed, and constitute an important new tool for species identifications. In particular, we describe the cuticular structures, defined as denticles, on the distal inner margin of the carpus of gnathopods 1 and 2. These structures may have a polygonal pattern or appear as comb scales, and may be arranged in one or more rows.