Extrafloral nectaries of an Atlantic Forest conservation area in Southeastern Brazil

ABSTRACT Although extrafloral nectaries (EFNs) are reported as extremely important to understand ecological interactions, the diversity of EFN-bearing plants remains underappreciated. In Brazil, studies are concentrated in Cerrado and extremely poorly known in other phytogeographic domains, such as Atlantic forest. Thus, this study provides one of the first checklists of angiosperms with EFNs in a protected area of the Brazilian Atlantic forest, bringing information about the richness, location of EFNs on the plant’s organs, as well as plant’s habit and conservation status. A total of 93 EFN-bearing species belonging to 61 genera and 29 families is reported, which corresponds to 16.5 % of the local flora. The vast majority has not been evaluated for their conservation status, and twenty species are endemic to the Brazilian Atlantic forest. Vines and trees are the predominant plant habits and EFNs are mostly found on leaves. More than half of the species (53.7 %) comprises new additions to the world list of EFN-bearing plants, including the first record in Dilleniaceae. Our findings show a large number of EFN-bearing plant species from a single and small protected area in the Brazilian Atlantic forest. It reinforces the lack of studies of this nature, where further investigations are strongly recommended.

摘要 尽管花外蜜腺（extrafloral nectaries, EFNs）对于解析生态相互作用具有至关重要的意义，但具花外蜜腺植物的多样性仍未得到充分认知。在巴西，相关研究多集中于塞拉多（Cerrado）生态区，而在大西洋森林等其他植物地理区系中的研究则极为匮乏。本研究编制了巴西大西洋森林某保护区内嵌有花外蜜腺的被子植物（angiosperms）的首批名录之一，涵盖了物种丰富度、花外蜜腺在植物器官上的着生位置、植物生活型以及保护现状等信息。本次研究共记录到29科61属共93种具花外蜜腺的植物，占当地植物区系的16.5%。其中绝大多数物种尚未开展保护现状评估，另有20种为巴西大西洋森林特有种。藤本与乔木为该区域的优势植物生活型，花外蜜腺多着生于叶片之上。超过半数（53.7%）的物种为全球花外蜜腺植物名录的新增类群，其中包括五桠果科（Dilleniaceae）的全球首次记录。本研究结果显示，巴西大西洋森林内一处单一小型保护区即蕴藏了大量具花外蜜腺的植物物种，这一发现也凸显了此类研究的不足，因此强烈建议开展更多相关调查研究。