Non-volant mammalian species richness in the ecotonal Brazilian midnorth: checklist for Maranhão State

Abstract: The state of Maranhão, located in the westernmost portion of the Northeast Region of Brazil, is characterized by a dynamic and unstable ecotone among the Amazon, Caatinga and Cerrado biomes that presents a high degree of biodiversity with high vulnerability to anthropogenic activities. Despite the enormous potential for sheltering high levels of species diversity and abundance, little is known about many aspects the state’s biodiversity, especially with regard to mammalian fauna. A capture-recapture methodology using live-traps was employed to inventory the non-volant, small mammal community. In addition, we recorded medium and large mammals based on direct and indirect observations, camera-trap surveys, and interviews. An extensive literature search of published research was also performed to maximize the elaboration of a complete mammal species checklist for Maranhão. A total of 89 non-volant mammal species, representing 9 orders and 27 families were recorded in the state of Maranhão. Of these taxa, 25.84% are included in the Brazilian Red List for endangered species, while 20 are considered as being endemic to Brazil. The preservation status of some areas, coupled with the strong presence of agro-pastoral environments, contributed to some unusual species occurrences, while the state’s ecotonal nature was noted by the numbers of species associated with the Amazon (N=65) and Cerrado (N=66) biomes.. Given the rapid development and effects of numerous anthropogenic impacts occurring in the state, it is a crucial time to quantify, even at specific scales, the environmental richness of Maranhão. The significant levels of biodiversity, high degree of endemism, and the presence of numerous rare and endangered species characterizes Maranhão as being among the most biologically important parts of Brazil. Nonetheless, many gaps in our basic knowledge regarding the biodiversity of this area remain, such that the execution of additional biological inventories is imperative, as are greater efforts to clarify certain species limits and necessary taxonomic revisions, most notably that for small mammals.

摘要：巴西东北部最西端的马拉尼昂州（Maranhão），地处亚马逊（Amazon）、卡廷加（Caatinga）与塞拉多（Cerrado）三大生物群系的动态不稳定生态过渡带，拥有极高的生物多样性，同时对人为活动具有高度脆弱性。尽管该区域具备承载极高物种多样性与丰富度的巨大潜力，但学界对马拉尼昂州生物多样性的诸多方面仍知之甚少，尤以哺乳动物类群为甚。本研究采用标记重捕法（capture-recapture），利用活捕笼对陆生非飞行小型哺乳动物群落开展编目调查；此外，通过直接与间接观测、红外相机调查以及访谈记录等方式，记录了该州的中大型哺乳动物类群。同时，我们全面检索了已发表的相关研究文献，以尽可能完善马拉尼昂州的哺乳动物物种完整名录。本次调查共记录到马拉尼昂州的非飞行哺乳动物共计89种，隶属于9目27科。其中25.84%的类群被列入《巴西濒危物种红色名录》，另有20种为巴西特有物种。部分区域的保护现状，加之农牧复合生境的广泛分布，催生了部分少见物种的出现；而该州的生态过渡带属性，可通过关联亚马逊生物群系（N=65）与塞拉多生物群系（N=66）的物种数量得到体现。鉴于该州正处于快速发展阶段，且面临多重人为活动的影响，即便仅在特定尺度下对马拉尼昂州的环境丰富度进行量化评估也已刻不容缓。该区域拥有极高的生物多样性水平与特有程度，同时分布有大量珍稀濒危物种，使其成为巴西生物多样性最重要的区域之一。尽管如此，我们对该区域生物多样性的基础认知仍存在诸多空白，因此开展更多的生物多样性编目调查势在必行，同时也需要投入更多精力厘清部分物种的分类界限，并开展必要的分类学修订——尤以小型哺乳动物类群为要。