The Atlantic Forest in the state of Rio de Janeiro is extremely fragmented and reduced in its original extension. Although there are a great number of studies related to the biome, few lists are available for this region. The present study seeks to get information on the mammals of a remnant forest in Serra da Concórdia, an area from which no information is currently available. The rapid mammal's survey was accomplished by use of pitfalls, live traps, transects, mist nets, and camera traps. We recorded 37 terrestrial species that represent 22.3 % of Rio de Janeiro state mammal species. Among the recorded species, six are endemic of the Atlantic Forest, one is endemic of the state, and eight are in the state list of threatened or presumably threatened species. The area presents great mammal richness and an increasing effort will probably reveal the presence of additional species.

Distance sampling is a widely used technique. However, the influence of several factors on the observations when using this technique, such as speed of the observers, microhabitat, weather, and method of detection, are still unknown. We aimed to evaluate the effect of various factors in the encounter rates and frequency of detection of mammalian species using the distance sampling technique with transects in an Atlantic Forest area, Ilha Grande, state of Rio de Janeiro, Brazil. We evaluated the effects of the forms of detection, sighting time, and the climate conditions on mammals samplings. Between December 2003 and May 2005, 128 transects were undertaken by a single observer, totalling 401.3 km and 382 hours. We recorded 163 individuals of nine species of mammals. Several factors affected our study using the distance sampling by linear transects, which include the animal activity period (i.e., object of study), followed by climate conditions, and transect location. We also found lower encounter rates in transects located in the north part of the island, because of the interference of tourists and the poaching pressure, which must be associated with the higher human densities in the north of the island that would inhibit the presence of certain species. This study highlights the importance of considering these variables when estimating mammal population sizes using distance sampling technique.

Alouatta guariba clamitans Cabrera, 1940 is an endemic species of the Atlantic Forest that occurs from south Bahia, Brazil, extending south to the province of Misiones, Argentina. In Rio de Janeiro state, the species was classified as threatened, indicating that attention is needed for the conservation of this taxon. Additionally, an outbreak of yellow fever spread throughout the southeastern states of Brazil from January 2017 until March 2018 seriously threatening Rio de Janeiro populations of the species. Herein, we aimed to provide the first estimates of A. g. clamitans encounter rate, density, and population size in the Ilha Grande State Park (PEIG), which is part of the Atlantic Forest biome of Brazil. Data were collected in two different periods, the first between December 2003 and May 2005, and the second from August 2009 to May 2010, and information on encounter rates and behavior was collected to better understand aspects of species' ecology. The estimated encounter rate in the first period through the distance sampling method was 0.04 ± 0.01 individuals per kilometer. Nine groups were recorded in the second period of the study, with 47 individuals along 3 km. Our estimates of encounter rate, density and population size were low and reinforces the need to initiate species monitoring and assess the impact that yellow fever outbreaks may have on PEIG populations. The results presented here can be a starting point to support future strategic actions for the species, to measure impacts and to the management of the species, and for a conservation program.

The spotted paca,Cuniculuspaca (Linnaeus, 1766), is a Neotropical, opportunistic, frugivorous caviomorph rodent, that inhabits primarily broadleaf forests. We aimed to provide the first estimates of density of C.paca for the Ilha Grande, an island located in the Atlantic Rain Forest biome of Brazil. Density and population size were estimated using the total number of individuals observed along each trail through the program DISTANCE 7. Our estimates of density and population size reinforces the importance of the Ilha Grande as an important reservoir of the species. Therefore, the results presented herein can be a starting point to support future action plans for the species, making predictions regarding the ecosystem and management and conservation of the spotted paca. Furthermore, the results can be used as a surrogate for other regions in which the species occurs.

Two lizard species that occur in northern Uruguay are poorly known: Stenocercus azureus and Hemidactylus mabouia. We sequenced the genes 12S and ND2 and estimated phylogenetic trees. The H. mabouia sequence found in Rivera City was unique and more closely related to a widely distributed haplotype found in Brazil, Argentina, and the Caribbean. The S. azureus from near Masoller (Salto) grouped with a sample of S. azureus from Bajada de Pena (Rivera). We encourage further sampling in order to assess the population structure of H. mabouia in Rivera City and to delineate potential conservation units of S. azureus in the region.