ESTUDOS ANATÔMICOS EM TRÊS ESPÉCIES DE Elaphoglossum SCHOTT EX J. SM. (DRYOPTERIDACEAE – SAMAMBAIA): UMA CONTRIBUIÇÃO TAXONÔMICA

Na Amazônia brasileira ainda são poucas as informações sobre as samambaias. Os trabalhos florísticos vêm sendo desenvolvidos principalmente em áreas de conservação. Grande parte desses estudos fazem referência à Dryopteridaceae como uma das famílias com maior riqueza específica, representada pelo gênero Elaphoglossum. Apesar de ser um gênero facilmente reconhecido pelas folhas simples e soros acrosticóides, a mesma facilidade não ocorre na determinação de suas espécies. A partir desta problemática, este trabalho objetivou caracterizar a anatomia de folhas estéreis e rizomas, bem como localizar os sítios de produção e/ou acumulação de compostos bioativos, nas espécies E. discolor, E. flaccidum e E. laminarioides, para inventariar caracteres que auxiliem na taxonomia do gênero. O material fértil foi submetido às técnicas de herborização, enquanto outra parte às técnicas usuais em anatomia vegetal, para confecção de lâminas e análise estrutural em microscopia de luz e eletrônica de varredura. Os testes histoquímicos foram realizados em secções a mão livre de acordo com os protocolos específicos. Ambas as espécies possuem: epiderme uniestratificada, sendo as paredes, em vista frontal, sinuosas em ambas as faces; são hipoestomáticas, predominando o tipo polocítico, com estômatos no mesmo nível das demais células epidérmicas; os feixes vasculares são bicolaterais na folha e anficrivais no rizoma; estelo do tipo dictiostelo; em cada feixe vascular há endoderme e periciclo, sendo envolvidos por bainha cortical lignificada; mesofilo homogêneo. Apenas E. laminarioides apresentou estômatos do tipo copolocítico e anomocítico, além de bainha cortical lignificada no pecíolo e apenas E. flaccidum apresentou margem em forma de bico e mesofilo com células braciformes. Quanto às características histoquímicas, observou-se que E. laminarioides foi a espécie que mais se destacou em relação a presença de compostos bioativos, devido ter apresentado resultados positivos para carboidratos neutros, lipídios ácidos e alcalóides. Apesar das espécies terem apresentado um padrão unificador em grande parte dos caracteres inventariados, foi possível distingui-las

On the true identity of Mendoncia “stellate” trichomes

ABSTRACT The present survey of leaf-blade trichomes of Mendoncia used SEM and light microscopy to investigate the diversity of trichome types in Neotropical and Paleotropical species of the genus. The eglandular trichomes are filiform, uniseriate, with asymmetric epidermal cells arranged radially around the trichome, these epidermal cells may be short or elongated, oriented in two groups. These cells, when elongated, are covered with epicuticular wax, forming smooth thick plates. African species have dendritic but not stellate trichomes. Character states such as number and length of basal cells were shown to overlap within the same species and therefore their use in isolation is not recommended for subgeneric classification of Mendoncia. Neotropical Mendoncia trichomes with well-developed epidermal cells arranged radially around the trichome appear to be unique to this group, without parallel in other plant families

The future of biotic indices in the ecogenomic era: Integrating (e)DNA metabarcoding in biological assessment of aquatic ecosystems

The bioassessment of aquatic ecosystems is currently based on various biotic indices that use the occurrence and/or abundance of selected taxonomic groups to define ecological status. These conventional indices have some limitations, often related to difficulties in morphological identification of bioindicator taxa. Recent development of DNA barcoding and metabarcoding could potentially alleviate some of these limitations, by using DNA sequences instead of morphology to identify organisms and to characterize a given ecosystem. In this paper, we review the structure of conventional biotic indices, and we present the results of pilot metabarcoding studies using environmental DNA to infer biotic indices. We discuss the main advantages and pitfalls of metabarcoding approaches to assess parameters such as richness, abundance, taxonomic composition and species ecological values, to be used for calculation of biotic indices. We present some future developments to fully exploit the potential of metabarcoding data and improve the accuracy and precision of their analysis. We also propose some recommendations for the future integration of DNA metabarcoding to routine biomonitoring programs.info:eu-repo/semantics/publishedVersio

Croton sect. Cyclostigma (Euphorbiaceae): anatomical and taxonomic novelties

Croton L. é um gênero megadiverso, amplamente distribuído, monofilético e que, até o momento, possui como única sinapomorfia os estames encurvados no botão floral. Já em nível infragenérico, não há sinapomorfias morfológicas que distingam a maioria das seções. Dentre os caracteres utilizados nas descrições taxonômicas de Croton, destacam-se as estruturas secretoras mostrando-se promissoras como subsídio para a taxonomia e filogenia, pois exibem diversidade morfológica e produzem compostos de natureza química complexa. No entanto, imprecisões em caracterizações anatômicas e descrições taxonômicas que não combinam parâmetros como a natureza química, a estrutura e período de atividade das estruturas secretoras, vêm causando equívocos principalmente quanto ao reconhecimento de coléteres e nectários extraflorais (NEF). Tais estruturas podem ocupar posição equivalente e possuir semelhanças morfológicas. O presente estudo tem como foco Croton seção Cyclostigma sensu stricto, plantas arborescentes e exclusivamente Neotropicais. As espécies desta seção são popularmente conhecidas como sangue de dragão devido à exsudação de látex avermelhado quando os troncos sofrem injúrias. A filogenia molecular de Croton seção Cyclostigma demonstrou uma evolução reticulada, com pouca resolução entre as diferentes linhagens. Neste estudo pretende-se ampliar e gerar uma base de dados mais robusta incluindo caracteres anatômicos foliares. Adicionalmente, a natureza química da secreção produzida pelas estruturas secretoras foliares e florais de C. echinocarpus e C. urucurana foi investigada visando esclarecer a classificação destas estruturas e apontar novas interpretações para o gênero. As amostras foram preparadas conforme metodologia usual para análises em microscopia de luz e eletrônica de varredura. Após descrição da anatomia foliar, foi construída uma matriz binária, a partir da qual foi calculada a distância, gerando um dendrograma de similaridade. Folhas e flores de Croton echinocarpus e C. urucurana apresentaram cinco tipos de estruturas secretoras, que foram similares em ambas as espécies. Os idioblastos secretam compostos de natureza mista, os laticíferos são não-articulados ramificados e coléteres e nectários produzem secreção hidrofílica. As glândulas marginais são coléteres do tipo padrão e as flores também apresentaram este tipo de coléter, uma novidade para o gênero. A análise conjunta da estrutura anatômica, histoquímica e período de atividade secretora foi essencial para permitir uma classificação precisa e assim discutir possíveis homologias das estruturas secretoras no gênero. A presença de diferentes tipos de tricomas estrelados, laticíferos não-articulados, além da ausência de NEF nas margens e tricomas lepidoto e fasciculado foram as principais características anatômicas que possibilitaram agrupar os representantes da seção Cyclostigma. Os caracteres anatômicos agregaram dados na descrição de um novo táxon. A partir da amostragem examinada, não foi confirmada a hipótese sobre a homologia entre idioblastos secretores na epiderme e tricomas secretores, assim como, sobre a generalização de laticíferos articulados em Crotonoideae. Embora não tenha um caracter anatômico único para a seção Cyclostigma, a combinação das características examinadas em diferentes níveis de agrupamento foi útil para demonstrar as semelhanças entre espécimes, estabelecendo a identidade taxonômica específica.Croton L. is a megadiverse genus, widely distributed species, monophyletic and that, up to now, possesses the curved stamens in flower buds as the only synapomorphy, and at the infrageneric level there are no morphological synapomorphies that distinguish most sections. Among the characters used in taxonomic descriptions of Croton, the secretory structures are particularly important as they have been promising on the suport of taxonomic and phylogenetic studies, taken in to account they exhibit morphological diversity and produce compounds of complex chemical nature. However, imprecisions in anatomical and taxonomic descriptions that do not match parameters as chemical nature, structure and activity period of secretory structures, have been causing mistakes especially for recognition of colleters and extrafloral nectaries (EFN). These structures may occupy an equivalent position and possess morphological similarities. The present study focuses in Croton section Cyclostigma s.s., arborescent plants and exclusively Neotropical. The species of this section are popularly known as dragon's blood due to the reddish latex exudates on trunks upon injuries. The molecular phylogeny of Croton section Cyclostigma showed a reticulate evolution with little resolution among the different lineages of Croton species investigated. This study aims to expand and produce a database including leaf anatomical characters. Additionally, the chemical nature of the secretion produced by leaf and floral secretory structures of C. echinocarpus and C. urucurana was investigated aiming to clarify the classification of these structures and to point new interpretations to the genus. Samples were prepared according to the methodology for analysis under light and scanning electron microscopy. A binary matrix was constructed based on the leaf anatomical description, after that the distance was calculated and a similarity dendrogram was generated. Leaves and flowers of Croton echinocarpus and C. urucurana present idioblasts that secrete mixed nature compounds, laticifers are non-articulated branched and colleters and nectaries produce hydrophilic secretion. The marginal glands are standard type colleters, which are also present in flowers that represents a novelty for the genus. The combined analysis of anatomical structure, histochemistry and secretory activity period was essential to accurate classification and thus discuss possible homologies of secretory structures in the genus. The presence of different types of stellate trichomes, non-articulated laticifers, besides the absence of EFN on the leaf margin and lepidote and fasciculate trichomes were the main anatomical features that made it possible to cluster the representatives of section Cyclostigma. The anatomical characters aggregated data in the description of a new taxon. From the examined sampling was not confirmed the hypothesis about the homology between secretory idioblasts in the epidermis and secretory trichomes, as well as about the generalization of articulated laticifers in Crotonoideae. Although has not a unique anatomical pattern for section Cyclostigma, the combination of features examined on different levels of clustering was useful to demonstrate the similarities between specimens, and to establish taxonomic identities.Fundação de Amparo à Pesquisa do Estado de Minas Gerai

Leaf anatomical features and their implications for the systematics of dragon's blood, Croton section Cyclostigma (Euphorbiaceae)

Establishing species limits in clades in Croton using characters from external morphology and common molecular markers has proved cumbersome, especially in Croton section Cyclostigma, a group of 50 Neotropical arborescent species commonly known as dragon's blood. Given this, we explored leaf and shoot apex anatomical characters for their utility in distinguishing species or groups of species in this section. We analysed 90 specimens belonging to section Cyclostigma and 14 specimens from related groups (sections Adenophylli, Cupreati and Sampatik), recording and describing 45 qualitative leaf characters. These characters were assembled into a matrix and analysed using statistical clustering methods based on similarity. Our results show that trichomes are one of the most diverse and variable anatomical features among the studied specimens. Novel anatomical features for Croton include the presence of a hypodermis and two previously unreported types of non-glandular trichomes. Although we did not detect a single anatomical character uniting section Cyclostigma, combinations of anatomical characters were useful to establish species limits and taxonomic identities within this section.ACF thanks FAPEMIG for the scholarship in Brazil during her doctoral degree, the CAPES foundation through PDSE (99999.009518/2014-02) supporting her stay at the Real Jardín Botánico-CSIC (Madrid) and the Programa de Capacitação Institucional (MPEG/MCTI) for the current CNPq research grant. RMSAM was supported by CNPq (477867/2013–8). RR was supported by a Visiting Scholar Fellowship to Brazil funded by FAPEMIG (CRA-BPV-00043-14) and CNPq research grant (477867/2013–8). Additional support was provided by Centro de Ciências Ambientais Floresta Escola (SECTES/UNESCO/HidroEX/FAPEMIG). We are grateful to two reviewers and the associate editor for their valuable suggestions and critical comments to earlier versions of this manuscri

Four New Species of Dragon’s Blood Croton (Euphorbiaceae) from South America

We describe and illustrate four new species of dragon’s blood trees (Croton sect. Cyclostigma) fromwestern SouthAmerica. Three of the species, Croton beckii from Bolivia and Peru, C. camposii fromPeru, and C. santamartensis fromColombia, grow inmontane Andean forest,whereas C. tumbesinus occurs in dry forest of the Tumbes/Piura ecoregion of western Ecuador and Peru. The characters that place them in Croton sect. Cyclostigma include the arborescent habit, the presence of reddish to yellowish latex, an indument of stellate trichomes, conspicuous and persistent stipules, acropetiolar/basilaminar nectary glands, and terminal inflorescences with bisexual cymules at the base. These new species give additional support for the Andean region being the main center of diversity of this Neotropical Croton clade, as well as being a region whose biodiversity knowledge is still incomplete.ACF was supported by a CNPq research grant and the Programa de Capacitaç~ao Institucional (MPEG/ MCTIC). MIOR was supported by a mobilization scholarship from the National Fund for Scientific Development, Technological and Technological Innovation-FONDECYT, CONCYTEC (Lima, Peru), for a two-month internship at the RJB-CSIC in 2017. RR received support from the Synthesys Programme (GBTAF-2834)Peer reviewe

Structural and histochemical aspects in leaves of six species of Anemia (Anemiaceae) occurring in rocky outcrops

Abstract Rocky outcrops are known for low humidity, rainfall and high solar radiation, factors that limit the development of some vegetables. However, some species of the genus Anemia occurring in these environments. Thus, understanding the anatomical characters present in these vegetables are important for botanical and biodiversity knowledge in rock fields. We described the leaf anatomy of six species of Anemia to identify characters adapted to rocky outcrops for ferns. Herbarium samples were rehydrated. Field-collected leaves, were also sampled, the material was subjected to standard anatomical study by light microscopy, and secretions were evaluated by histochemical of the secondary compounds, with ruthenium red, tannic acid, ferric chloride, lugol, Sudan black B, vanillin/hydrochloric acid, Dragendorff’s reagent and ponceau xylidine. Histochemical tests were positive for phenolic compounds, alkaloids, polysaccharides, and proteins in A. buniifolia, A. oblongifolia, A. presliana, and A. trichorhiza. Our findings revealed that several structural and histochemical characters of Anemia with trichomes, conical stegmatas, phenolic compounds, mucilages and alkaloids are related to reducing water loss, providing an adaptive value to species in extreme environments, such as rocky outcrops, in addition to new data relevant to the group taxonomy, such as the presence of amphistomatic leaves in A. trichorhiza