ABSTRACT Calcrete platforms covered by tightly packed individuals of the Etheriidae freshwater oyster Bartlettia stefanensis (Moricand 1856) forming small reefs were exposed in several spots of the Muru river, Acre, Brazil, during the 2024 drought. Freshwater oysters were known to colonize submerged laterite outcrops growing inside cavities; but the reef-like formations recorded in Acre represent a previously undescribed aquatic habitat probably at risk as the frequency of extreme droughts increase due to climate change.

ABSTRACT The Amazon bioeconomy produces byproducts that have potential as ingredients in aquaculture feed. This study aims to evaluate nutritional composition, digestibility, and attractiveness of six regional byproducts - Artisanal Fish Waste Meal (FM), Defatted Brazil Nut Meal (BN), Cassava Leaf Meal (CL), Decaffeinated Guarana Bagasse (GB), Defatted Murumuru Meal (MU), and Defatted Ucuuba Meal (UC) - for use as tambaqui (Colossoma macropomum) feed. The byproducts had diverse nutrient profiles, with FM providing significantly more digestible protein and energy, followed by BN and CL. Attractiveness tests indicate that CL and BN are approached more rapidly and consumed more readily. BN and CL have potential as plant-based alternatives, due to their digestibility and attractiveness to the fish. In contrast, GB and UC were limited in both digestibility and feeding stimulation. We suggest that the byproducts FM, BN, and CL can easily be integrated into tambaqui diets, supporting sustainable aquaculture practices in the Amazon. Additional research can determine how to optimize processing and inclusion to fully exploit the functional properties of these ingredients while ensuring cost-effective and environmentally friendly fish farming.

ABSTRACT Species variation in relation to habitat differences may offer valuable insights into understanding population divergence and speciation itself. In central Amazonia, phenotypic and phenological variation of four bryophytes - Octoblepharum albidum, Octoblepharum pulvinatum, Leucobryum martianum and Pilosium chlorophyllum - were investigated among white-sands and terra-firme plateaus to examine whether habitat differences relate to trait variation. In three of the four species, sexual expression was significantly more restricted temporally in the drier habitat type (white-sands forest) than that observed in more mesic, terra-firme plateau forests. Contrary to global patterns of reproductive behavior for bryophytes, male expression was notably more prevalent than female expression for three of the four species. Furthermore, significant infra-specific phenotypic variation among habitat types associated with multiple measured traits (e.g., total leaf length, apex length, base width) illustrate the evolutionary potential of Amazonian bryophytes in the framework of habitat differentiation. Future priorities should focus on resource allocation dynamics and ecophysiology in a phylogenetic context to better understand the role of habitat differentiation in speciation processes among Amazonian bryophytes.

ABSTRACT The pantropical Vanilla is the most species-rich genus among Vanilloideae (Orchidaceae). With 38 species, Brazil is the center of diversity for Vanilla. Several of the Brazilian taxa are considered obscure, as species boundaries are often unclear when studies are performed exclusively on dried specimens. This is the case of Vanilla sprucei Rolfe, a rare taxon with ephemeral flowers that has been referred to Brazil based on a specimen collected in the Colombian Amazonia. We present data confirming its occurrence in Brazil, together with a taxonomic evaluation of this poorly-known species including a detailed, illustrated morphological description. An epitype for V. sprucei based on Brazilian material is designated. The geographical distribution of this taxon is presented. The phylogenetic position of V. sprucei within Vanilla and its relationships with Neotropical congeners are discussed based on a phylogenetic hypothesis. Vanilla sprucei emerges at a basal node among the non-membranaceous, Neotropical Vanilla clade. The inclusion of V. sprucei in the molecular data matrix reinforces the V. trigonocarpa group as polyphyletic. For this reason, further infrageneric rearrangements will be necessary. Preliminary evaluation of the species´ conservation status according to IUCN criteria indicate a global status of Endangered, with subpopulations in Brazil assessed as Critically endangered.

ABSTRACT Lemnoideae is a yet little known taxon in Brazil in taxonomic and distributive terms, given the few records for the country, especially in the Amazon region. Here, we present the first record of Lemna minuta Kunth for the state of Pará, providing a description of the species, its occurrence in Brazilian territory, and additional comments. This contributes to expanding the knowledge of the species’ distribution in the Amazon.

ABSTRACT The Amazonian megadiversity remains understudied and underestimated due to the region’s vast size, environmental heterogeneity, and inaccessibility. With increasing threats to the biome, it is crucial to map current knowledge before it is lost. This study addresses Linnean (species description), Wallacean (species distribution), and Darwinian (genetic knowledge) shortfalls for Amazonian anurans, quantifying what remains unknown. We reviewed species descriptions, analyzed occurrence data, and evaluated available genetic sequences and phylogenetic uncertainty. Species descriptions have grown over time, peaking around 2000. We estimate that 1,525 species exist in Amazonia, but only 766 (based in the species shapefiles) or 810 (based in the occurrence data) were found. Richness was highest in northern and western Amazonia, while remote areas far from urban centers remain undersampled. Only two genes (mitochondrial 12S and 16S) have been sequenced for more than half of the known species and are available in open databases, while phylogenetic uncertainty predominates in most clades. Regions such as Gurupa Várzea and Cordillera Central Paramo are especially under-sampled. Our results show that taxonomic, distribution, and genetic shortfalls are complementary rather than overlapping, indicating that different regions and species groups require different research strategies. This study highlights major knowledge gaps and provides a framework to guide future efforts in taxonomy, biogeography, and evolutionary studies of Amazonian anurans, supporting conservation planning in one of the most diverse regions on Earth for one of the most diverse and threatened taxonomic groups.

ABSTRACT White-sand vegetation (campinarana) is a type of vegetation restricted to oligotrophic and highly leached white sand soils in the Amazon phytogeographic domain that includes grassland to forest phytophysiognomies. Campinaranas cover about 5% of this phytogeographic domain and are impacted by various anthropic activities that put plant species, especially endemic ones, at risk. Myrtaceae has significant representativeness in oligotrophic edaphic environments, but floristic and taxonomic studies on the family in campinaranas are still few and geographically limited. We present a checklist of Myrtaceae species known from campinaranas of the Brazilian Amazon based on the survey of herbarium specimens and literature data in order to assess the level of endemism of these species for this vegetation type. We compiled occurrence records of 72 species and six genera. Myrcia and Eugenia were the genera with the highest number of species. Overall, 38 species (53%) occurred only in the Amazon and two were endemic to campinaranas (Eugenia campina and Myrcia psammophila). Four species are new records for the Brazilian Amazon: Blepharocalyx salicifolius, Eugenia hatschbachii, Myrcia anceps and Myrcia racemosa. The specific richness of Myrtaceae in Brazilian campinaranas is likely to be underestimated since extensive areas, especially those farther from the riverbanks, in the states of Amazonas and Roraima, have not yet been intensively surveyed.

ABSTRACT The thermal modification of wood is a process that alters its chemical composition, aiming to improve technological properties such as dimensional stability, reduction of equilibrium moisture content, homogeneity, or color. In this context, this study aimed to evaluate the colorimetry and chemical properties of the wood of Parkia pendula (angelim-saia) and Simarouba amara (marupá) that was thermally modified by different methods. Three treatments were evaluated: T1 (pre-treatment in an oven for one hour at 120 °C and treatment in an oven at 180 °C for three hours); T2 (pre-treatment in an autoclave at 125 °C for three hours under 1.2 kgf cm-2 and treatment in an oven at 180 °C for three hours); and T3 (without pre-treatment, with sample treatment in vegetable oil). The thermally modified wood was evaluated in relation to untreated wood for structural chemical composition (extractives, lignin, holocellulose and ash content), colorimetric parameters defined through the CIELAB (Commission Internationale de l´Eclairage) system and total color variation. We detected a significant increase in extractives content and a decrease in holocellulose and lignin content in T3 for both species, which can be explained by the impregnation of oil in the wood samples. The thermal modification caused the surface darkening of the wood of both species, which was more pronounced in P. pendula. Despite the colorimetric change, there was no chemical damage to the wood.

ABSTRACT Brazil stands out as one of the largest manufacturers of MDF (medium density fiberboard) in the world. The industries are concentrated in the south and southeast of the country and are primarily based on the use of Pinus and Eucalyptus wood, which are available in extensive planted areas. In the northern region, there is only one MDF industrial plant. Despite an abundance of potential raw materials in this region, there is a lack of studies on native species wood and their industrial waste utilization for MDF production. The present study aimed to evaluate the properties of MDF manufactured from a mixture of cultivated paricá (Schizolobium amazonicum) wood and wood waste from native Amazonian species. The study assessed the isolated effects of different proportions of the raw materials and panel thicknesses on MDF properties. Panels were produced, and samples were obtained for testing. Using standard procedures, the following properties were determined: density, water absorption, thickness swelling, internal bonding, static bending, and resistance to screw withdrawal. The results revealed a significant impact of the analyzed variables on some physical and mechanical properties of MDF. With the exception of internal bonding, all other properties of the evaluated MDF panels met the specified regulatory requirements for use in furniture manufacturing. It is concluded that mixtures of the assessed raw materials have great potential for MDF production in the furniture industry. However, adjustments in the production process are recommended to improve the internal bonding property.

ABSTRACT Croceous glands are visible structures defined by their rounded shape and yellowish color. They have great taxonomic importance, being used to delimit the Timutua section, one of the 14 sections of the subgenera Polygala, genera Polygala, the most representative of the family Polygalaceae, with about 120 species recorded in Brazil. However, detailed information about the nature of croceous glands is still missing. Thus, this study aimed to characterize the origin, structure, and function of the croceous glands in the floral structures, fruits, leaf blades, and stems of Polygala adenophora. Samples of P. adenophora at different developmental stages (flower buds, fully developed flowers and fruits), as well as stems, and leaves collected from the 1st, 3rd, 6th, and 9th nodes were obtained from a coastal area in Pará state, Brazil. The samples were fixed in FAA50 or buffered neutral formalin and submitted to light microscopy and scanning electron microscopy. Histochemical tests were carried out for lipophilic and hydrophilic compounds. Our results showed that the croceous glands are secretory cavities and ducts of schizolysigenous origin, present since the beginning of the development of vegetative and reproductive organs. The cavities and ducts produce a lipophilic compound consisting of essential oils and lipids. We hypothesize that this exudate possibly has a protective function, acting against pathogen and herbivore attacks.