Taxonomia e distribuição potencial da tribo Cocoseae Mart. (Arecaceae) no Estado do Maranhão

Abstract

The Cocoseae tribe, belonging to the family Arecaceae, has representatives in many plant formations, being composed by several species with the sociocultural and economic value for local populations. In Maranhão, the lists of species of this group that are pointed out in the literature present inconsistencies regarding the composition and taxon distribution. In view of the need for more information about this tribe in the State, the present dissertation had the following aims: (I) to provide taxonomic data to help formally recognize the native species of the region, as well as to provide ecological information and conservation status for all the taxon; (II) to elaborate potential distribution models for species categorized as Data Deficient in the previous proposal, in order to direct future collection efforts to the field. In order to fulfill objective (I), the botanical material deposited in several herbaria of Brazil and abroad was analyzed, as well as material from expeditions carried out in some municipalities of the State, which were identified and described based on specialized literature. The literature and the samples had their labels analyzed to obtain information about the vernacular names, distribution, ecology and for the evaluations of conservation status. In order to reach the goal (II), the algorithm Maximum Entropy was used, which elaborated projections of the suitable areas for the species classified as Deficient Data, from the compilation data by digital platforms, visited collections and literature, besides the selected environmental variables. We obtained as result of the taxonomic study, the occurrence confirmation of 26 native species in Maranhão, distributed in seven genera. Bactris Jacq. ex Scop. was the most representative genus with seven species, followed by Attalea Kunth (six spp.), Syagrus Mart. (five spp.), Astrocaryum G. Mey. (three spp.), Desmoncus Mart. (three spp.), Acrocomia Mart. (one sp.) and Allagoptera Nees (one sp.). All species had the main recognition structures described and presented in taxonomic comments besides an identification key. Information about vernacular names, occurrence environments and ecology was available, as well as the conservation status of all taxon. Nine species were identified as Least Concern (LC), three were Near Threatened (NT), five were Vulnerable (VU), three in Endangered (EN) and six in Data Deficient (DD). In relation to the potential distribution models, all the generated maps allowed to identify the priority areas for the accomplishment of future samplings. In addition, they showed a clear pattern of contraction in potential area in the face of degradation level of the State vegetal cover. The Amazonian species, for example, had reductions of up to 49.9% of the potential area; this reduction was the reflection of the deforestation of this biome in the last decades. Finally, it should be highlighted that this dissertation contributed to a greater understanding of the native palm trees in Maranhão State, confirming species and increasing the possibilities of occurrence. However, new studies are necessary and should prioritize the collection of data of species with information deficits, besides being based on the formulation of effective conservation measures for the taxon listed as threatened.