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：位于巴西东北部最西端的马拉尼昂州（Maranhão），其境内存在一处动态且不稳定的生态过渡带（ecotone），衔接亚马逊（Amazon）、卡廷加（Caatinga）与塞拉多（Cerrado）三大生物群系，拥有极高的生物多样性，同时极易受到人为活动的干扰。尽管该区域具备孕育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，在哺乳动物区系方面尤为突出。本研究采用活捕诱捕（live-traps）结合标记重捕法（capture-recapture）的方法，对该州的非飞行小型哺乳动物群落开展了系统清查；此外，通过直接与间接观测、红外相机（camera-trap）调查以及访谈记录，采集了中型及大型哺乳动物的相关数据。同时，本研究还对已发表的相关文献进行了系统性检索，以尽可能完善马拉尼昂州哺乳动物物种名录。本次调查共记录到马拉尼昂州的非飞行哺乳动物共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（Brazilian Red List for endangered species）》，另有20种为巴西特有种。部分区域的保护现状，加上农牧交错环境的广泛分布，促成了一些罕见物种的出现；而该州的生态过渡带属性，则可从关联亚马逊生物群系的物种（N=65）与关联塞拉多生物群系的物种（N=66）的数量中得以体现。鉴于该州正经历快速发展与多重人为活动影响，即便仅针对特定尺度开展量化研究，摸清马拉尼昂州的环境物种丰富度也已刻不容缓。该区域极高的生物多样性水平、高度的特有性，以及众多珍稀濒危物种的存在，使其成为巴西生物多样性最为重要的区域之一。尽管如此，学界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清查工作迫在眉睫，同时还需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，其中尤以小型哺乳动物类群的相关修订最为关键。