The Reserva Biológica do Tinguá (REBIO Tinguá) is a protected area in the state of Rio de Janeiro comprising around 26,000 ha of Brazilian Atlantic Forest. We present an updated floristic inventory of Leguminosae tree species in the REBIO Tinguá. Pre-existing herbarium collections and field expeditions carried out in 2021 and 2022 were used as the basis for (i) assembling a comprehensive taxonomically verified checklist of the legumes, (ii) revealing species distribution patterns across the Submontane (‘tingua_s’) and Montane/High Montane Dense Ombrophilous (‘tingua_ma’) Forest physiognomies of the REBIO Tinguá, and (iii) an UPGMA-based floristic similarity analysis to compare the REBIO Tinguá with 28 other areas of Atlantic Forest in Rio de Janeiro state. Of the total 67 legume tree species identified, 35 are endemic to the Atlantic Forest, six are new occurrences for the area, and seven are listed under different threat categories. The legume-based similarity analysis showed clusters that largely reflect the environmental heterogeneity of the region, where ‘tingua_ma’ is grouped with Macaé de Cima, Mendanha and Santo Aleixo, while ‘tingua_s’ is grouped with Paraty Mirim, Pedra Branca, Poço das Antas, Tijuca and REBIO Union. Our study shows that new records can be made for the REBIO Tinguá, despite it being one of the most thoroughly inventoried areas in the state. Our results reinforce the importance of the REBIO Tinguá for biodiversity conservation, because of its great extent, altitudinal amplitude, and above all, its central position in the state, integrating the Mosaico Central Fluminense and the Tinguá–Bocaina biodiversity corridor.

The rapid urbanization process in recent decades has altered the carbon cycle and exacerbated the impact of climate change, prompting many cities to develop tree planting and green area preservation as mitigation and adaptation measures. While numerous studies have estimated the carbon stocks of urban trees in temperate and subtropical cities, data from tropical regions, including tropical botanic gardens, are scarce. This study aimed to quantify the aboveground biomass and carbon (AGB and AGC, respectively) stocks in trees at the Rio de Janeiro Botanical Garden arboretum, Rio de Janeiro, Brazil. Our survey included 6793 stems with a diameter at breast height (DBH) ≥ 10 cm. The total AGB was 8047 ± 402 Mg, representing 4024 ± 201 Mg of AGC. The AGB density was 207 ± 10 Mg·ha⁻¹ (AGC = 104 ± 5 Mg·ha⁻¹), which is slightly lower than the density stored in Brazil’s main forest complexes, the Atlantic and Amazon forests, but much higher than in many cities worldwide. Our results suggest that, in addition to their global importance for plant conservation, tropical botanic gardens could function as significant carbon sinks within the urban matrix.

Background and aims – The neotropical genus Tachigali comprises about 75 recorded species, including names described in Sclerolobium, synonymised in 1993 in Tachigali based on morphological, molecular, and anatomical characters. Most species are found in northern South America and the Atlantic Forest. However, some species are exclusively found in the savannas of central Brazil (Cerrado), Bolivia, and Paraguay. The Tachigali species from northern South America and Central America has already been revised. However, the extra-Amazonian Tachigali species were not correctly typified due to the impossibility of examining all syntypes. Therefore, the present work aims to present the nomenclatural review of the extra-Amazonian species of Tachigali. Material and methods – The list of accepted extra-Amazonian Tachigali names and their basionyms was made and verified through online databases. The original descriptions were consulted online or in the Rio de Janeiro Botanical Garden Library. The type specimens were examined in virtual herbaria and through visits to the B, IAN, G, K, M, NY, P, R, RB, US, and W herbaria. The International Code of Nomenclature of algae, fungi, and plants was followed for the type designation and nomenclatural notes. Key results – The nomenclatural review was carried out for 32 names. A total of 15 lectotypifications, representing 12 Tachigali species, and a new combination for Tachigali rubiginosa is proposed herein. Furthermore, the nomen dubium Sclerolobium macrophyllum is presented. Conclusion – Our study provides the nomenclatural review for the extra-Amazonian Tachigali species, including notes about the type materials, collectors, and authors of all species names, in addition to the holotype and lectotype images.

The Reserva Biológica do Tinguá is a protected area located in Rio de Janeiro state, Brazil. It is part of the Atlantic Forest domain and primarily features Dense Ombrophilous Forest, ranging from lowland to submontane, montane, and highland vegetation types. The Reserva Biológica do Tinguá is critically important for conservation, ranking among the priority areas for protecting the biodiversity of the Atlantic Forest, as well as local water supply. Understanding and accessing the floristic list within the regions is essential to developing effective conservation strategies. We utilize herbaria databases to create a comprehensive list of plant species based on revised taxonomic data. The updated list of vascular plants recorded in Rebio Tinguá is available in the “Catálogo de Plantas das Unidades de Conservação do Brasil” and is presented here with additional details on species richness, endemism, and conservation status. The Reserva Biológica do Tinguá contains 1,301 species of vascular plants, including 1,133 angiosperms, one gymnosperm, and 167 are ferns and lycophytes. Of these species, 52,2% are endemic to the Atlantic Forest. There are 97 threatened species, of which five are considered Critically Endangered (CR), 57 Endangered (EN), and 36 Vulnerable (VU) at national level. Among the threatened species, 86 are endemic to the Atlantic Forest. The number of records and species richness in this area are notably high, comparing to Atlantic Forest standards. Protecting areas like the Reserva Biológica do Tinguá in densely populated urban centers presents considerable challenges due to environmental degradation, including air and water pollution and extraction of natural resources. Recognizing the ecological significance and promoting floristic studies of the remaining fragments of the Atlantic Forest is essential for biodiversity conservation ensuring overall environmental integrity.

Background and aims – The taxonomy of any group is the sum of publications scattered throughout the literature added to the application of the International Code of Nomenclature for algae, fungi, and plants. A significant part of being a group specialist is the ability to apply a Linnaean binomial correctly and resolve conflicts in the light of the Code. Over the years, Ouratea crassinervia has been misidentified as O. verticillata, a species restricted to southern Rio de Janeiro and northern São Paulo states. Additionally, the name O. crassinervia began to be applied as an accepted name in Central America, with O. costaricensis and O. curvata mistakenly as its synonyms. On the other hand, there was no mention of O. crassinervia in species lists or monographs for the Brazilian Flora until 2020, when it appeared as a synonym for O. curvata, repeating another misinterpretation. Material and methods – From 2021 to 2024, we conducted fieldwork in northern Rio de Janeiro. Furthermore, specimens for all “dracenoid” species were studied in several Brazilian herbaria, and some were examined online. The morphological data of the description were obtained through the analysis of both living and dried specimens observed in the field and the herbarium. The assessment of O. crassinervia conservation status was according to the IUCN Red List Categories and Criteria. Key results and conclusion – Ouratea crassinervia is endemic to the low Atlantic Forest in the northeastern part of Rio de Janeiro, Brazil, and limited to the south by the Guanabara Bay. Morphologically, O. crassinervia is similar to O. cauliflora, O. dorata, and O. verticillata from the Brazilian Atlantic Forest, O. ramiflora from the Amazon, and O. costaricensis and O. theophrasta from Central America, due to the “dracenoid” habit, but can be easily distinguished by its terminal inflorescence and larger flowers. This work provides a discussion of the architectural model and the inflorescences for each species in the group and an emended key for the “dracenoid” Ouratea species.

Here, we describe and illustrate the new species Ouratea oberdanii Fraga & Deccache, which is named after Dr Oberdan José Pereira. This new species is found in the mountainous regions of the evergreen Atlantic Forest in the Brazilian state of Espírito Santo. Ouratea oberdanii is similar to O. linearis (A.Gray) Sastre & Offroy and O. parviflora (DC.) Baill. It can be distinguished by its habit, with branches that are reclining and pendulous, the leaf vein pattern, with the presence of intramarginal veins, its persistent stipules and bracts, and the presence of indumentum on the midvein of the adaxial surface of petals and on the anthers. We also provide a distribution map, preliminary conservation status assessment, taxonomic notes, and an identification key for Ouratea species from Espírito Santo.