In the state of Mato Grosso, studies aiming to investigate the diversity and richness of bats are still scarce. In the present study, the chiropteran fauna of eastern Mato Grosso (Brazil) was investigated at four sites representing the Cerrado savanna biome with different degrees of anthropogenic impact, in the municipality of Nova Xavantina. Surveys were conducted between January and December, 2010, with a total of 48 nights of mist-netting. A total of 423 bats were captured, representing 25 species distributed in five families. A greater abundance of individuals was recorded at all sites during the rainy season, with considerable variation being observed over the course of the year in species richness and composition, and the abundance of bats. Species richness and bat abundance were higher in the better preserved habitats in comparison with the impacted areas. The timing of foraging activities appeared to vary among the specimens and there was a progressive increase in activity until 19:30 h, with a marked decline after 22:30 h. The ecological diversity (Shannon-Wiener index) of the bat community within the study area was H′ = 2.37.

In Brazil, Vampyrum spectrum has been recorded in the Amazon forest, Caatinga, Pantanal, and in the Cerrado of Tocantins. The only previously known record for the Mato Grosso state is more than 50 years old, in a Pantanal area. This paper provides the first record of the species in a Cerrado area of this state, in the municipality of Nova Xavantina, west central Brazil.

Given the substantial lacunas in the understanding of the occurrence and distribution of bat species in the eastern portion of the Brazilian state of Mato Grosso (Araguaia basin), this study presents an inventory of the species known to occur in the region, highlighting the areas sampled adequately and the species known to occur in conservation units. Georeferenced records of the occurrence of bat species in the region were obtained from published studies, scientific collections, through either the SpeciesLink network or directly from the curator, as well as the capture of specimens by our research group between 2008 and 2013. A 0.5° x 0.5° (latitude/longitude) grid was added to the map of the region for the quantification of the bat species richness of each grid cell. A total of 63 chiropteran species were recorded for the study area. Only 10 of the 30 grid cells had records of bats, and just three contained more than 20 species, and were considered to be sampled adequately on a minimal level. Bat species have been recorded in three conservation units, two state and one municipal. The number of species recorded represents 82.7% of the total of chiropterans known to occur in Mato Grosso, although 12 species were recorded in the state for the first time, reinforcing the paucity of data available on the distribution of bats in the region. The high bat species richness recorded in the present study reinforces the importance of eastern Mato Grosso, a transition zone between the Amazon forest and the Cerrado savanna of central Brazil, for the conservation of Neotropical chiropterans.

There are two species of Neotropical Round-eared bats, Tonatia bidens Spix, 1823 and Tonatia saurophila Koopman & Williams, 1951, which present highly similar morphological characteristics that can lead to errors of identification. Specimens originally identified as T. bidens have recently been reclassified as T. saurophila, and the only karyotype documented previously for these species was 2n = 16, FN = 20. In the present study, specimens of Tonatia collected in the municipality of Barra do Garças, in the Brazilian state of Mato Grosso, were analyzed morphologically, using conventional cytogenetic techniques (C-banding, Ag-NOR, and CMA₃), and through sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene. In the specimens morphologically identified as T. bidens, the diploid number (2n) was 26, and the fundamental number (FN), 38, while in T. saurophila, 2n = 16 and FN = 20, which is the karyotype also described previously for T. bidens. The dendograms obtained with sequences of the COI marker resulted in the formation of two distinct groups between T. bidens and T. saurophila, consistent with the two species, with a high sequence divergence value (14.22%). Distinct clades were also observed between T. bidens and the other phyllostomines analyzed in this study, with T. bidens also close to Phyllostomus hastatus (14.18% of sequence divergence).