Autor: José L. Passos Cordeiro

José Luís Passos Cordeiro, J.L.P. Cordeiro

Composition and frequency of capture of bat assemblages in a landscape mosaic in northern Pantanal, Mato Grosso, Brazil

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Influence of landscape patches on species richness and frequency of bats was evaluated in a cattle ranch in northern Pantanal wetland. Besides the lack of information on bats in areas modified by ranching, land use and the seasonal flooding in the Pantanal wetland certainly affects bat fauna composition. Twenty-seven (27) species were captured, distributed in five families. Phyllostomidae predominated with 16 species, followed by Vespertilionidae with five species. Species richness and frequency of captures varied according to the landscape mosaic, presenting positive association to less altered areas. Species more sensitive to environmental disturbances were captured in the most conserved areas, associated to palm forests (acuri palm forest; Scheelea phalerata, acuri palm tree) and flooded forest (cambará forest; Vochysia divergens). Our data suggest that even vegetation units in extensively deforested areas are valuable for the maintenance of some species of bats, either because they offer many of the resources they need or because they are spatially arranged in order to facilitate the joint use of the landscape patches.

Composição e frequência de captura de assembleias de morcegos em um mosaico da paisagem no Norte do Pantanal, Mato Grosso, Brasil. A influência das manchas da paisagem sobre a riqueza e frequência de captura de quirópteros foi avaliada em uma fazenda de gado no norte do Pantanal. A falta de informações sobre os quirópteros em áreas modificadas pela pecuária, o uso da terra e as inundações estacionais no Pantanal certamente são fatores que limitam o entendimento da composição da quiropterofauna da região. Foram capturadas 27 espécies, distribuídas em cinco famílias. Phyllostomidae predominou com 16 espécies, seguido por Vespertilionidae com cinco espécies. A riqueza de espécies e a frequência das capturas variaram de acordo com o mosaico da paisagem, apresentando associação positiva a áreas menos alteradas. Espécies consideradas mais sensíveis a distúrbios ambientais foram capturadas nas áreas mais conservadas, associadas a florestas de palmeiras (floresta de acuri; Scheelea phalerata, palmeira de acuri) e florestas inundadas (floresta de cambará; Vochysia divergens). Os dados sugerem que mesmo unidades de vegetação em extensas áreas desflorestadas são valiosas para a manutenção de algumas espécies de quirópteros, seja por oferecerem muitos dos recursos que necessitam ou por estarem espacialmente dispostos de forma a facilitar a utilização conjunta das manchas da paisagem.

Karyotypes of Brazilian representatives of genus Zygodontomys (Rodentia, Sigmodontinae)

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In this article we are reporting two cytotypes found in representatives of Zygodontomys genus trapped in two localities of Brazilian Amazon. From the locality of Surumú (Roraima) were analyzed 12 individuals (cytotype 1) which showed 2n = 86 / FN = 96–100, presenting the two largest pairs (1 and 2) as subtelo-submetacentrics, 4 or 5 medium to small biarmed pairs, the remainder being acrocentric. In Tartarugalzinho (Amapá) 7 specimens which displayed 2n = 84 / FN = 96–98 (cytotype 2) were caught. In both cytotypes the sexual pair is composed by a large submetacentric X chromosome and a median subtelocentric Y chromosome. By G-banding the largest pairs as well as the sex chromosomes could be identified. The C-bands occurred at the centromere of the majority of the autosomes and the short arm of the X and the whole Y chromosomes were heterochromatic. The NOR-bands were prevalently seen at the short arm of one medium and one small acrocentric pairs. Comparing the individuals studied in Brazil with those reported in Venezuela is observed that, although the same or similar diploid numbers, the morphology of the chromosomes of these taxa is quite different, the karyotypes of the specimens from Brazil having a smaller number of biarmed elements.The sexual pair is distinct also, the difference basically concerning to the size of the Y chromosome. Whether these karyotype differences may correspond to different morphological taxa is a subject that deserves further investigations.