Résumé
ABSTRACT Preserved riparian vegetation usually has greater environmental complexity than the riparian vegetation modified by human actions. These systems may have a greater availability and diversity of food resources for the species. Our objective was to evaluate the effect of changes on the structure of the riparian forest on species richness, beta diversity and composition of butterfly species in the Cerrado of Mato Grosso. We tested the hypotheses that: (i) higher species richness and (ii) beta diversity would be recorded in more preserved environments; and (iii) species composition would be more homogeneous in disturbed habitats. For hypothesis testing, the riparian vegetation of eight streams were sampled in four periods of the year in a fixed transect of 100 m along the shores. The richness of butterfly species is lower in disturbed than in preserved areas. However, species richness is not affected by habitat integrity. Beta diversity differed among sites, such that preserved sites have greater beta diversity, showing greater variation in species composition. In addition, beta diversity was positively affected by environmental heterogeneity. A total of 23 of the 84 species sampled occurred only in the changed environment, 42 were exclusive to preserved sites and 19 occurred in both environments. The environmental change caused by riparian forest removal drastically affects the butterfly community. Therefore, riparian vegetation is extremely important for butterfly preservation in the Cerrado and may be a true biodiversity oasis, especially during the dry periods, when the biome undergoes water stress and resource supply is more limited.
Résumé
The aim of our study was to characterize Cerataphis brasiliensis Hempel, an aphid of native palm tree of tropical savannas (cerrado), and to record intraspecific variation. We found two parthenogenetic forms of apterous viviparae females of C. brasiliensis. We differentiate the two forms through measurable and qualitative characters: (i) length of cephalic horns, (ii) number of antennal segments, (iii) presence or absence of wax glands, (iv) location of siphunculi.
O objetivo desse estudo foi caracterizar Cerataphis brasiliensis Hempel, um afídeo de palmeiras nativas de savanas tropicais (cerrado), e registrar a variação intra-específica. Foram encontradas duas formas de fêmeas partenogenéticas viviparas ápteras de C. brasiliensis, diferenciadas por caracteres mensuráveis e qualitativos: (i) comprimento dos chifres cefálicos, (ii) número de segmentos da antena, (iii) presença ou ausência de glândulas de cera, (iv) localização do sifúnculo.