ABSTRACT The family Pycnothelidae comprises medium to small-sized spiders that construct silk tubes under stones or logs or dig burrows in open environments. In Argentina, Acanthogonatus centralis Goloboff, 1995 and Stenoterommata platensis Holmberg, 1881 are two species commonly found in central region, associated to the mountainous grasslands or to the La Plata River Basin. The Tandilia mountainous grassland is an extended belt located southeastern Buenos Aires province, Argentina. Although some pycnothelid spiders are distributed close to this mountainous system, they are not recorded in Tandilia. Through niche modeling we attempt to evaluate the influence of bioclimatic variables in shaping the distribution of these species and explore their absence in the mountainous belt under past, present and future climatic conditions. We found that Tandilia is a non-suitable area for the establishment of the populations of these species with the exception of Stenoterommata platensis under a future scenario of climatic change.
ABSTRACT Mangroves are coastal ecosystems that exist in the transition zone between terrestrial and marine environments, typical of tropical regions, and they occur in areas with frequent tidal submersion. These ecosystems shelter the species Rhizophora mangle L. (Rhizophoraceae), a mangrove tree that has rhizophores, stem projections that serve as a substrate for a variety of encrusting, sedentary animals and macroalgal species. This study was carried out in an estuarine mangrove on the Acaraú River, located in northeastern Brazil, with the aim of determining the benthic community stablished over R. mangle rhizophores. Accordingly, five trees of this species were chosen, and subsequently, three rhizophores were selected from each tree, totaling fifteen sampled rhizophores, from which all associated macrobenthos were removed. All collected organisms were identified and rhizophores were evaluated for species richness, composition, density, diversity, frequency, equitability and dominance. In addition, vertical zonation of the organisms in rhizophores was determined. The benthic community was characterized by the predominant presence of the phylum Mollusca (Bivalvia and Gastropoda) and the phylum Annelida (Polychaeta). We showed the existence of a vertical zonation of the organisms in the substrate. Understanding the community structure in the rhizophores can facilitate more detailed and experimental studies to comprehend the distribution and even the biological interactions in these environments.
Lotic ecosystems are biodiverse environments that form different mesohabitats suitable for some species of crustaceans, such as those of the genus Hyalella, endemic to the Americas. In the state of Santa Catarina, anew species- Hyalella insulae- was recently described- the first insular species of Hyalella in Brazil, on the island of Florianopolis. The species was identified in the Municipal Natural Monument of Lagoa do Peri (MONA), south of the island, which has a large source of freshwater in the state, consisting of two watersheds: Cachoeira Grande and Ribeirao Grande. This study aims to analyze the spatial distribution of H. insulae in two mesohabitats (backwater and rapids) of these watersheds. Specimens were sampled in stretches of rifles and pools between winter/2010 and summer/2012, in three 1st to 3rd order streams inserted in the two watersheds, totaling 192 samples. It was observed that most samples with the presence of H. insulae occurred in the Cachoeira Grande watershed. The mean total abundance of H. insulae was higher in the pools stretches of Cachoeira Grande streams when compared to Ribeirao Grande. In the streams of both watersheds, in addition to males and females, juveniles of H. insulae were collected, which demonstrates that the species is reproducing in these streams. In addition, a higher concentration of dissolved oxygen and lower values of water temperature, water velocity, electrical conductivity and alkalinity were observed in Cachoeira Grande stream. This study demonstrated the preference of H. insulae for pools stretches of streams in Cachoeira Grande, which has primary and dense vegetation, unlike Ribeirao Grande, where areas with secondary vegetation and evidence of anthropic actions are observed in the surroundings. Thus, this research demonstrated the importance of studies regarding the distribution of endemic species, as well as the conservation and preservation of island streams and their biota.
ABSTRACT The genus Platyrrhinus Saussure, 1860 is one of the most speciose within the Phyllostomidae family in the Neotropical region, with 19 documented species worldwide, nine of which are found in Brazil. Platyrrhinus guianensis Velazco and Lim, 2014 was first recorded in the Guiana Shield, followed by a record in the Brazilian Amazon. This study represents the second record of P. guianensis in Brazil, specifically in the Maranhão (MA) Amazon biome (Turiaçu/MA - 01°39’36”S and 45°22’12”W). Morphological, craniodental, and molecular characters were employed for species identification. The specimen exhibited a dark brown dorsal fur, a conspicuous wide and white dorsal stripe, dark gray ventral fur, a forearm length of 38.5 mm, a short skull without a fossa in the scaly root of the zygomatic arch, with two stylar cusps on the posterior crest of the upper second premolar, one stylar cusp on the anterior crest of the lower second premolar, and upper internal incisors bilobed and convergent. Molecular results supported the morphological identification, confirming the occurrence of P. guianensis in the Maranhão Amazon. Molecular results provide the first public sequence of P. guianensis for the 16S rRNA gene and a new sequence for the COI gene, which will be useful in future studies for the species. These results supported the morphological identification, confirming the occurrence of P. guianensis in the Maranhão Amazon. This record extends the known distribution of this species approximately 1428.32 km to the east within the Amazon biome in Brazil.
Grazing intensity is one of the main factors that shape vegetation structure, influencing the grassland bird community. Tall grass birds, including several threatened species, are depending on low intensities or exclusion of grazing, which is rarely practiced in Pampa. In this study we evaluate how grazing intensities affects the bird community in Brazilian Pampa grasslands. We established three transect lines, one each grazing treatment (moderate and low intensity, and on an area with cattle exclusion). During 13 months, transects were sampled monthly to record the diversity and abundance of bird species. All three areas presented very similar species richness, ranging from 50 to 54 species, and diversity (H') ranging from 2.79 to 2.95. The abundance was favored by the decrease in intensity and the exclusion of grazing. In general, shortgrass bird species were more representative in the area under moderate grazing, while tallgrass birds were favored by low intensity and grazing exclusion. The taller and denser vegetation, in areas less impacted by livestock, was especially important for endangered species, such as Culicivora caudacuta Vieillot, 1818 and Sporophila cinnamomea Lafresnaye, 1839, providing shelter, perches and substrate for building and fixing nests. We corroborate the need for areas with distinct grazing intensities, forming a mosaic with different heights of vegetation, maintaining the grassland bird diversity. However, more areas with low intensity or exclusion of grazing are needed, on which several threatened species depend. Although, even these areas must be managed, avoiding the encroachment of excessive woody vegetation, which can lead to the deterioration of grassland vegetation, affecting the associated birdlife.
