Alessandra Angélica de Pádua Bueno

New Species and New Records of Endemic Freshwater Crabs from the Atlantic Forest in Southern Brazil (Anomura: Aeglidae)

Abstract Two new species of freshwater anomurans, Aegla pomerana and Aegla muelleri (Decapoda: Anomura: Aeglidae), are described from the Itajaí River basin, the major basin of the Atlantic range, located in the northeastern part of the state of Santa Catarina, Brazil. The new taxa can be distinguished from their congeners based on both morphological and molecular evidence (the nuclear gene 28S, and the mitochondrial genes 12S, 16S, COI, and COII). Based on molecular data, A. pomerana has a phylogenetic relationship with A. leptodactyla, but morphologically these two species differ in several characters. Aegla muelleri is a member of the same clade as A. leptochela, but several morphological characters distinguish the two species. New records of occurrence of A. jarai and A. odebrechtii, which occur in the same hydrographic basin, are provided.

Two new subterranean species of Hyalella Smith, 1874 (Crustacea: Amphipoda: Hyalellidae) from Brazil

Two new species of Hyalella from Brazil are described. Hyalella veredae sp. n. shows the following characters: eyes reduced or absent in some specimens; antenna 1 and antenna 2 of similar size, and a curved seta on the inner ramus of male uropod 1. Hyalella formosa sp. n. is characterized by the absence of eyes, antenna 1 longer than antenna 2 and a curved seta on the inner ramus of male uropod 1. The species were found on caves located in two private properties, both under the impact of agricultural activities, which demonstrates a potential threat to these subterranean environments.

A new troglobiotic species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from Southeastern Brazil

The genus Hyalella Smith, 1874 is typical from the continental American waters and show high levels of endemicity. In Brazil, the occurrence of 12 species was reported, of which only Hyalella caeca Pereira 1989 is troglobiotic. A new species was found in a cave, Gruta da Toca, located near Itirapina city, state of Sao Paulo, Brazil. This species represents the second troglobiotic for the genus in Brazil.

TWO NEW SPECIES OF HYALELLA (AMPHIPODA, DOGIELINOTIDAE) FROM BRAZIL

Two new freshwater species of amphipods from Brazil are described here. Hyalella xakriaba n. sp. occurs in the hydrographic basin of the Sao 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.

A new species of freshwater amphipod (Dogielinotidae, Hyalella) from Southeastern Brazil

To the present 57 species of Hyalella were described for Americas, 15 of them found in Brazil, which is among the most diverse countries for this genus. This work aims to describe a new Hyalella species with benthic habits which is found in a water source on Southeastern Brazil. It is mainly characterized by a wide truncated process formed near the dactylus insertion on gnathopod 2, besides both coxal and sternall gills present on pereonits 2 to 7. This work improves the knowledge on biodiversity about Hyalella species.

Reproductive aspects of Hyalella carstica (Amphipoda: Hyalellidae) in a natural environment in southeastern Brazil

The reproductive aspects of populations are important determinants of their ability to maintain themselves throughout time. In the case of amphipods from the genus Hyalella Smith, 1874, the reproductive period is easily determined by the presence of ovigerous females and pre-copula pairs in the population. This study evaluated the fecundity, pairing patterns and reproduction period of Hyalella carstica Bastos-Pereira and Bueno, 2012 in a karst environment in the West of Minas Gerais, Brazil. Monthly, from April, 2010 to April, 2011, amphipods were sampled using a hand net with 15 cm diameter and 250 µm mesh size. In the laboratory, animals were sexed and measured, and the ovigerous state of females was evaluated. Couples in pre-copula and ovigerous females were found throughout the year, with the exception of the dry months (September−November). During drought, the streams superficial water dried out, and only a few refuges for the population remained. Although couples were found in all months with a water flow, a higher number of unpaired males and females was found after the dry season. In all months, ovigerous females were more abundant than non-ovigerous, and the relationship between head length and the number of eggs in the marsupium was positive. Most eggs were in the first developmental stage, although all other stages were found before the dry season. Considering the frequency of pre-copula pairs, as well as ovigerous females, the reproduction in this H. carstica population seems to be continuous throughout the year, without a distinct peak.

A new troglobiotic species of Hyalella (Crustacea, Amphipoda, Hyalellidae) with a taxonomic key for the Brazilian species

The freshwater crustaceans from the order Amphipoda occur mainly in cold and temperate climates. However, in the tropics, these animals can be more abundant in subterranean environments, where the temperatures are milder than in surface. Despite being accepted that the number of species of freshwater amphipods in South America is lower when compared to other regions, recent descriptions have shown that its diversity is certainly underestimated. In this study, a new species of the genus Hyalella is described for Brazil, the fourth troglobiotic species of Hyalella for the country and the sixth in the world. The new species was found on the epikarst of a cave in São Paulo state, Southeastern Brazil. Besides, the new species shows typical characteristics from organisms adapted to the subterranean environments, a pattern also observed in the other troglobiotic species of the genus.

Dynamics of a Natural Population of a Hyallelid Amphipod from Brazil

Hyalella longistila is a freshwater amphipod found in streams in southeastern Brazil. We examined temporal variations in the population dynamics of this species by analyzing its abundance, size frequency distribution, proportion of mating pairs and brooding females, sex ratio and recruitment, as well as the possible influence of environmental variables on such parameters. Samples were made in a stream in the state of Minas Gerais from March 2012 to February 2013. The size frequency distribution was polymodal for most of the months, with more than one maximum for both juveniles and adults. The maximum size attained by females (brooding and non-brooding) was higher than in males and the mean size of males (paired and unpaired) was higher when comparing with paired and unpaired females, respectively. Hyalella longistila seems to reproduce continuously but more intensively twice a year, in the middle of winter and end of spring. Recruitment occurred during several months (April, May, October, November, and December 2012), which could have affected the observed polymodal distribution. It is likely that this continuous breeding activity was possible due to the abundant macrophyte stand where the population inhabits, which could have provided constant shelter and feeding for individuals, but this aspect still needs to be investigated further. Moreover, a positive effect of dissolved oxygen on the frequency of brooding females, as well as of temperature on the abundance were recorded. Our results can help future researches in the conservation of aquatic ecosystems as a whole, more specifically for the preservation of Hyalella longistila and its use as a test organism.

A new species of Hyalella (Crustacea: Amphipoda: Hyalellidae) from Itatiaia National Park, Brazil: an epigean freshwater amphipod with troglobiotic traits at 2,200 meters of altitude

A new species of the freshwater amphipod Hyalella Smith, 1874 is described for the plateau of the Itatiaia National Park, located between the states of Minas Gerais and Rio de Janeiro, southeastern Brazil. This is the first Brazilian species of Hyalella found at more than 2,200 meters of altitude. The specimens were found in a small stream, buried under rocks, in the higher area of the Park. The main morphological characteristics that differentiate the new species are the extreme reduction of the size of the uropod 3, absence of apical setae on telson, absence of comb-scales on gnatopods 1 and 2, absence of curved seta on inner ramus of uropod 1 and sternal gills tubular on pereonites 3 to 7. The new species presents similarities with some cave species of the genus, apparently being troglophile and that is the process of adaptation to the hypogean habitat. The importance of creating new protected areas for the conservation of Hyalella in Brazil is discussed.