Rafaela Bastos-Pereira

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.

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 Spelaeogammarus (Amphipoda: Bogidielloidea: Artesiidae) with an identification key for the genus

There are five described species of the cave-dwelling amphipods of the genus Spelaeogammarus, all of them inhabiting caves on the Brazilian state of Bahia. A new species of this genus is here described, which is closely related to the already known species S. santanensis and S. titan. Spelaeogammarus sanctus sp. nov. differs from its congeneric species basically by the presence of more than 18 bifid setae on the dorsal margin of uropod 3 outer ramus and telson with one apical and two subapical stout setae, while the other species generally present less setae on the third uropod and more setae on telson. An identification key and an updated table of the Spelaeogammarus species diagnosis are provided, as well as a multivariate statistical approach of morphological variations among the species.

Anophtalmic and epigean? Description of an intriguing new species of Hyalella (Amphipoda, Hyalellidae) from Brazil

The absence of eyes in Hyalella (Hyalellidae, Amphipoda) is typical of obligate groundwater-dwelling species. However, a new intriguing blind amphipod of this genus was found in epigean streams from the Iron Quadrangle (state of Minas Gerais, Brazil). Hyalella troglofugia sp nov. presents antenna 1 shorter than antenna 2, gnathopod 1 propodus inner face with four setae, gnathopod 2 propodus posterior margin longer than palm, dactylus slightly longer than palm, pereopod 5 shorter than others and uropod 3 shorter than telson. The absence of eyes and presence of reduced U3 and pereopods of H. troglofugia sp nov. may suggest that such species also inhabits interstitial subterranean spaces. Moreover, the presence of the new species on streams associated to distinct hydrological zones indicates that this species may be present in different types of subterranean habitats of the region. We hypothesize that at least part of the population of this species may have left the subterranean environment looking for food and when out of this habitat it preferentially inhabits high water flow stretches of the stream in function of predation avoidance.

Are laboratory studies on behavior of troglobitic species always trustful? A case study with an isopod from Brazil

There is a huge lack of information regarding the natural history of subterranean species, particularly focusing on aspects of the behavioral ecology of Brazilian cave fauna. In the present work, we aimed to describe and evaluate the behavioral repertoire of Xangoniscus itacarambiensis (Isopoda, Styloniscidae) through observations in the field and laboratory and also by means of complementary experiments. Overall, we recorded 25 spontaneous behaviors. Besides describing the physical habitat, we recorded some intraspecific interactions, agonistic and territorial behaviors, as well as the amphibian habit. There was a direct relationship between the size of travertine dams where they live (measurements of length and width) and the mean number of individuals, although there was no significant correlation with the pool depth. Behaviors observed in the laboratory differed qualitatively and quantitatively from those observed in the field, with individuals more active in the latter. This scenario alerts about the significant behavioral alteration of such isopods when removed from their natural habitat, what must be considered in future behavioral studies including troglobites given their natural sensitivity to environmental changes.

Figure 3 In Spelaeogammarus Uai (Bogidielloidea: Artesiidae): A New Troglobitic Amphipod From Brazil

FIGURE 3. Spelaeogammarus uai sp. nov. Paratype male, 9.98 mm, ISLA 14963. Scale bars: 200 µm.