Introduction: Pentaclethra macroloba is a hyperdominant tree in the Amazon estuary of great socioeconomic importance for the region because the oil from its seeds is a powerful herbal medicine. Objective: We aimed to characterize the morphological structure, the morphological adaptations in response to the daily flooding of the Amazon estuary and the biogeographic area of P. macroloba. Methods: Detailed description of the external morphology, from germination to the adult tree, was obtained from individuals located in floodplain forest, Northeast Amazonia. The occupation area and the geographical extension of P. macroloba were determined from point of geographical coordinates of botanical samples deposited in the digital collections of Mobot and SpeciesLink. Results: Adult individuals have adapted structures in response to daily flooding, such as: adventitious roots to increase respiratory efficiency and lenticels in the trunk, serving as a connection point for oxygen transport between the root and the aerial part. Dried fruit favours the activation of the explosive dehiscence mechanism, allowing the seed to be expelled long distance. Deltoid shape of the seed allows water fluctuation and more efficient dispersal. Seedling is phanerocotylar hypogeal and with one pair of reserve cotyledons that provide the seedling an extra source of energy to escape the flood. Germination rate was 78 % and the speed was 0.2 seeds.day-1. Circular buffer method revealed the presence of 123 subpopulations of P. macroloba distributed in a radius of 5 699 943 km² across the Neotropical region. Conclusions: Much of the morphological structures of P. macroloba are adaptive and evolutionary responses to the periodically flooded environment of the Amazon estuary, showing that these environments select the trees, best adapted, to inhabit the flood. P. macroloba has a wide geographical area denotes the plasticity of adapting to different environments, which may justify its monodominance in some regions.

Pouteria kossmanniae (Sapotaceae, Chrysophylloideae), a new species from Central Amazonia, is here described. It is known from the Manaus region, Amazonas, Brazil, and is found in non-flooded upland forests, known as terra firme. Illustrations are provided in addition to geographic distribution, with a comparison of the morphological and spectral (near-infrared) differences between P. kossmanniae and its very similar species Pouteria macrophylla, Pouteria manaosensis, and Pouteria rodriguesiana. The species is naturally common in some urban forest fragments, but since only a low number of subpopulations is known, we assign P. kossmanniae the preliminary conservation status of “Endangered”.

Anais do 40º Encontro Regional de Botânicos - Regional MG, BA, ES (978-65-5941-087-3) - Modelagem Preditiva Da Distribuição Atual De Ecclinusa Guianensis Eyma (Sapotaceae, Chrysophylloideae) Na Bacia Amazônica

Giant trees in the Amazon serve as critical carbon sinks and underpin diverse forest ecosystems. Yet, these emergent giants are increasingly vulnerable to climatic change, jeopardizing their distribution and ecological niches. Here, we integrate ecological niche modeling with LiDAR, forest inventory, global repository data, and bioclimatic variables to reconstruct and forecast the distribution of Amazonian giant trees under past, present, and future climate scenarios (SSP1-2.6 and SSP5-8.5) across multiple biogeographic provinces. Employing MARS, Random Forest, MaxEnt, and GAM algorithms, we assess the influence of key climatic drivers, such as isothermality, maximum temperatures, and precipitation patterns, on habitat suitability for two emblematic species: Dinizia excelsa and Goupia glabra. Our analyses reveal that while both species exhibit distinct climatic responses, Tall trees obtained by LiDAR and Dinizia excelsa are particularly sensitive to heightened temperature extremes, notably in the Guiana Shield and Roraima Provinces. In contrast, Goupia glabra displays a broader tolerance to precipitation variability. Under the high-emission scenario (SSP5-8.5), projections indicate a loss of up to 45 % of suitable habitat by 2080, especially in southern provinces such as Xingu-Tapajós, where drought frequency and temperature extremes are expected to intensify. Conversely, the low-emission scenario (SSP1-2.6) may foster habitat stability or modest expansion in the northern Amazon. These findings underscore the urgent need for targeted conservation strategies to safeguard critical refugia and enhance ecosystem resilience in the face of global climate change.