Checklist preliminar de angiospermas em uma área ao sul do Rio Madeira (Manicoré, Amazonas, Brasil)

Abstract

Despite containing the largest biodiversity of the planet, the Amazon rainforest still hides part of its richness, which for many reasons, most of its areas remain undersampled. For Brazil, approximately 33,300 species of angiosperms are listed, where more than 12,000 of these are for the Amazon and more than 8,500 for the state of Amazonas, but estimates of the total number of species are much higher. Due to the large extent of the Amazon rainforest, research has focused on isolated and easily accessible locations. Thus, much of the Amazon basin shows no evidence of having been botanically well researched, there is little information available on plant diversity distribution. Located to the south of the Madeira River, the municipality of Manicoré has a high number of phyto-units, which may indicate, at first, the existence of a greater diversity of plant species. However, Manicoré is included among areas of low botanical knowledge, with a high proportion of unidentified species, which may contain many undescribed species. Therefore, the objective of this paper is to present a preliminary checklist of angiosperms from the municipality of Manicoré. To compile this list of species, the records of angiosperm collections for the municipality of Manicoré were verified in the database of the BRHAMS system, the Herbarium Collection of the National Institute for Amazonian Research - INPA and in the digital collection of the Reference Center and Environmental Information - CRIA, besides being made 28 botanical expeditions, which totaled about 90h of sampling effort in the field. A total of 801 species, 409 genera and 106 families were listed for the Manicoré municipality. The richest family was Fabaceae (117 spp.), followed by Euphorbiaceae (35 spp.), Rubiaceae (34 spp.), Apocynaceae (30 spp.), Melastomataceae (29 spp.), Moraceae (27 spp.), Arecaceae (24 spp.), Myrtaceae (20 spp.), Malvaceae (19 spp.), Annonaceae and Burseraceae (18 spp. Each), representing 46.3% of the listed species. Distributed among the distinct phytophysiognomies of the municipality of Manicoré, 45.7% (366 spp.) of the angiosperms in this checklist are represented by trees, 27.5% (220 spp.) shrubs, 13.2% (106 spp.) herbs, 4.7% (38 spp.) lianas, 3.5% (28 spp.) herbaceous vines, 3.2% (26 spp.) subshrubs and 2.2% (17 spp.) Palm trees. Our data record 47 new occurrences for the State of Amazonas according to the Flora do Brasil 2020 list, and of these new occurrences, 12 are also the first record for the Northern Region of Brazil. Of the twenty-eight botanical expeditions carried out in our study, 240 individuals belonging to 202 species, 145 genera and 63 families were collected, contributing 25.2% of the total species listed, making the collection points of these botanical expeditions the areas with the highest record of angiosperm species of Manicoré. However, we verified the existence of collection gaps in many areas, especially in the Center of the municipality, indicating that much of the region was not botanically researched. In addition, in just 90h of field sampling effort, we identified a new species of Mandevilla Lindl, endemic to the southern Amazon region. We also found that among the municipalities of the southern region of the Madeira River, Beruri, Tapauá, Apuí, Novo Aripuanã and Manicoré are, respectively, those with the largest angiosperm botanical collection gaps. It can be concluded that although still undersampled, the flora of Manicoré shows to present a great species richness. Floristic and phytosociological studies should be carried out, mainly in the poorly or unsampled areas, to verify the occurrence of a probable larger number of species. Therefore, this preliminary angiosperm checklist is the basis for further botanical studies for this region. Key-word: Amazon Forest, Brazilian Flora, Botanical collections