ABSTRACT Humiria balsamifera is an infraspecific complex of high phenotypic variation and widely distributed in northern South America. Leaf traits are traditionally considered the most relevant taxonomic characters for varietal level delimitation in the group. However, substantial phenotypic overlap among vegetative characters complicates taxonomic diagnoses in this complex. The objective of this study was to quantify and analyze phenotypic variation among individuals of the complex at a continental scale using uni- and multivariable analyses to assess whether morphometric analyses detect discontinuities. Secondarily, these quantitative data were used to test whether phenotypic similarity was related to geographic distance. Twenty- five quantitative and 27 qualitative character traits did not overtly reveal a topology corresponding to traditional varietal classification, nor to geographic structure. However, petiole length alone revealed a definitive separation of H. balsamifera var. guianensis (together with another recognized species Humiria wurdackii, and variety H. balsamifera var. laurina) from the rest of the taxa. Our results highlight substantial morphological overlap among vegetative and reproductive characters including those used in identification keys, and no morphological discontinuities suitable for clearly separating taxa within the complex were encountered demonstrating a future need to integrate multiple sources of information, including molecular data, to resolve this complex.

RESUMO Avaliamos a dinâmica populacional local de duas espécies epífitas, Syrrhopodon helicophyllus e Thysananthus amazonicus, ao longo de seis anos de 2014-2020, tanto antes quanto depois do incêndio que ocorreu na Campinarana localizada na Amazônia Central. Não observamos diferenças gerais na abundância de colônias na árvore hospedeira ao longo do tempo antes do evento de incêndio em 2019. No entanto, a abundância de colônias muda ao longo do gradiente vertical em direção ao microambiente mésico, o que permite persistir durante o evento El Niño de 2015-2016, e recuperado nos anos seguintes. Além disso, observamos que as colônias de ambas as espécies de briófitas diminuíram drasticamente após o incêndio em 2019, levando à perda completa das espécies em algumas das árvores hospedeiras estudadas Os impactos diretos das mudanças climáticas com o aumento de incêndios e secas nas florestas da Amazônia Central resultarão na perda da biodiversidade local epífita, especialmente nas florestas isoladas como as Campinaranas.

ABSTRACT We evaluated the local population dynamic of two epiphytic species, Syrrhopodon helicophyllus and Thysananthus amazonicus, over six years from 2014-2020, both before and after the fire event which occurred in the white-sand forest (Campinarana) located in Central Amazon. We did not observed an overall differences on colony abundance on the host tree over time before the fire event in 2019. However, colony abundances shifts along the vertical gradient towards mesic microenvironment which allow to persist during the El Niño event of 2015-2016, and recovered in the following years. Moreover, we observed that colonies of both bryophyte speciesdrastically declined after the fire event in 2019, leading to a complete loss of the species in some of the host tree studied. The direct impacts of climate change with an increased fire and drought events in Central Amazon forests will result in the loss of epiphyte local biodiversity, especially in the unique isolated white-sand forests.

Resumo Este estudo apresenta uma descrição detalhada, ilustração e comentários morfológicos de Sacoglottis guianensis e Sacoglottis mattogrossensis, as únicas espécies de Humiriaceae registradas para as cangas da Serra dos Carajás, no estado do Pará. Sacoglottis guianensis é uma espécie de ampla distribuição na América do Sul. Por outro lado, S. mattogrossensis ocorre ao sul da Amazônia e na Mata Atlântica, estendendo-se até São Paulo. Em Carajás, ambas espécies ocorrem nas cangas e nas matas baixas na transição da canga aberta para a Floresta Ombrófila.

Abstract This study brings detailed descriptions, illustrations and comments on the morphology of Sacoglottis guianensis and Sacoglottis mattogrossensis, the only representatives of Humiriaceae occurring in the canga of Serra dos Carajás, Pará state. Sacoglottis guianensis is widely distributed in South America while S. mattogrossensis occurs in the Southern Amazon and Atlantic Forest extending southward to São Paulo. In Carajás, both species are found in the canga and transitional areas between open canga and the rainforest.

Dichaea é o maior gênero da subtribo Zygopetalinae e possui sua maior diversidade de espécies na América do Sul. Diante disto, este trabalho teve o objetivo de descrever uma nova espécie de Dichaea ocorrente na região norte do Brasil, Dichaea bragae Valsko, Krahl & Holanda. A nova espécie foi coleta ao norte de Manaus em área de floresta ombrófila e floresceu em cultivo. O epíteto é em homenagem ao Dr. Pedro Ivo Soares Braga (in memorian), orquidólogo que realizou vários estudos na Amazônia brasileira. A nova espécie possui afinidade com espécies de Dichaea seção Dichaeopsis, contudo são diferenciadas vegetativamente e na morfologia do labelo.

Dichaea is the largest genus of the subtribe Zygopetalinae and holds it's the highest species diversity in South America. Therefore, this study aims to describe a new species of Dichaea, which occurs in northern Brazil, Dichaea bragae Valsko, Krahl & Holanda. The new species was collected in the north of Manaus in an area of ombrophilous forest and flowered when cultivated. The epithet honors Dr. Pedro Ivo Soares Braga (in memoriam), orchidologist who conducted several studies in the Brazilian Amazon. This new species show a affinity with Dichaea tenuis C. Schweinf., however it is differentiated both vegetatively and on labellum morphology.