Filogenia de Croton subgênero Adenophylli (Griseb.) Riina, B.W. Van Ee & P.E. Berry (Euphorbiaceae) e revisão das espécies de C. seção Adenophylli Griseb. ocorrentes no Brasil
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Data
2022-08-01
Autores
Sodré, Rodolfo Carneiro
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Universidade Estadual Paulista (Unesp)
Resumo
Croton é o décimo primeiro gênero mais diverso de Angiospermas com cerca de 1300 espécies dispersas pelos trópicos, 712 delas americanas. Quatro subgêneros são reconhecidos para Croton, sendo C. subg. Adenophylli exclusivamente americano e composto por duas seções: C. sect. Adenophylli e C. sect. Cyclostigma, além de três espécies sem posição seccional definida. Croton sect. Adenophylli é a maior do gênero com ca. 170 espécies e seis subseções: Adenophylli, Caribaeus, Laceratoglandulosus, Meridionalis, Pungentes e Velamea. Croton subg. Adenophylli e suas infracategorias têm sido consideradas monofiléticas, mesmo que a amostragem utilizada para realizar os estudos filogenéticos compreenda menos de 40% das espécies. A seção Adenophylli reúne táxons reconhecidos pelo hábito geralmente subarbustivo ou arbustivo com tricomas estrelados, folhas com ou sem glândulas no ápice do pecíolo, base e, ou margem da lâmina, inflorescências com címulas unissexuais, flores pistiladas usualmente sésseis ou subsésseis e columela do fruto com três apêndices ascendentes e usualmente inflados ventralmente. Croton sect. Adenophylli repete a distribuição de seu subgênero e embora seja bem delimitada morfologicamente, é uma das mais complexas e pouco estudadas taxonomicamente do gênero. No Brasil, a seção Adenophylli é uma das mais diversas com cerca de 50 espécies de norte a sul do país, mas reconhecidas, sobretudo, a partir de estudos desenvolvidos no século XIX (e.g., Flora Brasiliensis) e frequentemente encontradas em herbários nacionais sem identificação ou equivocadamente identificadas. Essa tese teve como principais objetivos: a) reconstruir filogenias para C. subg. Adenophylli a partir de uma amostragem que contemple a diversidade morfológica e de habitats de suas espécies, com intuito de testar seu monofiletismo, e o de suas infracategorias; b) determinar a posição sistemática de espécies não posicionadas em nenhuma das subseções ou seções do subgênero Adenophylli; c) propor uma classificação para o subgênero Adenophylli baseado nas filogenias obtidas, e, d) revisar a taxonomia das espécies da seção Adenophylli ocorrentes no Brasil. As reconstruções filogenéticas foram feitas pelos métodos de Máxima Parcimônia, Máxima Verossimilhança e Análise Bayesiana baseada em sequências do DNA plastidial (trnL-F) e nuclear (ITS 1+5.8S+ITS2), enquanto a revisão contemplou tanto coletas e observações das espécies em campo, como estudos de coleções herborizadas e de literatura especializada. Os resultados da tese são apresentados sob a forma de dois capítulos, o primeiro deles tratando da filogenia de Croton subg. Adenophylli, na qual amostramos 119 espécies, recuperamos a maioria das seções e subseções como monofiléticas, estas últimas com circunscrições ampliadas, e propomos Croton sect. Pulegiodorus e C. sect. Pycanthi para acomodar espécies sem posição sistemática ao nível de seção definida. O segundo capítulo trata da revisão taxonômica das espécies de Croton seção Adenophylli ocorrentes no Brasil, onde são reconhecidas 23 espécies contrastadas em uma chave, descritas, ilustradas, mapeadas e comentadas quanto a distribuição geográfica, estado de conservação, preferências ambientais, épocas de floração e frutificação, relacionamento morfológico e história taxonômica.
Croton is the eleventh most diverse genus of Angiosperms with about 1300 species dispersed throughout the tropics, 712 of them American. Four subgenera are recognized for Croton, of which Croton subg. Adenophylli exclusively American and composed by the sections Adenophylli and Cyclostigma, and three species without a defined sectional position. Croton sect. Adenophylli is the largest of the genus with ca. 170 species and six subsections: Adenophylli, Caribaeus, Laceratoglandulosus, Meridionalis, Pungentes and Velamea. Croton subg. Adenophylli and its infracategories have been considered monophyletic, even though the sampling used to carry out phylogenetic studies comprises less than 40% of the species. The section Adenophylli includes taxa recognized by their habit subshrubby or shrubby with stellate trichomes, leaves with or without glands at the apex of the petiole, base and/or margin of the blade, inflorescences with unisexual cymules, usually pistillate flowers sessile or subsessile and fruit columella with three ascending appendages and usually ventrally inflated. Croton sect. Adenophylli repeats the distribution of its subgenus and although it is morphologically well delimited, it is one of the most complex and taxonomically understudied of the genus. In Brazil, the section Adenophylli is one of the most diverse of the genus, with about 50 species distributed from north to south of the country, recognized mainly from studies developed in the 19th century (e.g., Flora Brasiliensis) and often found in local herbaria without identification or mistakenly identified. This thesis had as main objectives: a) reconstruct phylogenies for C. subg. Adenophylli from a sampling that contemplates the morphological and habitat diversity of its species, in order to test its monophyly, and hat of its infracategories; b) determine the systematic position of species not placed in any of the subsections or sections of the subgenus Adenophylli; c) propose a classification for the Adenophylli subgenus based on the phylogenies obtained, and d) review the taxonomy of species from the section Adenophylli occurring in Brazil. Phylogenetic reconstructions were performed using Maximum Parsimony, Maximum Likelihood and Bayesian Analysis based on plastid (trnL-F) and nuclear (ITS 1+5.8S+ITS2) DNA sequences, while the review included collections and observations of the species in field, and studies of herborized collections and specialized literature. The results of the thesis are presented in the form of two chapters, the first of which deals with the phylogeny of Croton subg. Adenophylli, in which we sampled 119 species, we recovered most sections and subsections as monophyletic, the latter with expanded circumscriptions, and we propose Croton sect. Pulegiodorus and C. sect. Pycanthi to accommodate species without systematic position at level of section. The second chapter deals with the taxonomic review of the species of Croton section Adenophylli occurring in Brazil, for which 23 species are recognized, contrasted in a key, described in detail, illustrated in their morphological nuances, represented by images, mapped and commented on the geographic distribution, conservation status, environmental preferences, flowering and fruiting times, morphological relationships and taxonomic histories.
Croton is the eleventh most diverse genus of Angiosperms with about 1300 species dispersed throughout the tropics, 712 of them American. Four subgenera are recognized for Croton, of which Croton subg. Adenophylli exclusively American and composed by the sections Adenophylli and Cyclostigma, and three species without a defined sectional position. Croton sect. Adenophylli is the largest of the genus with ca. 170 species and six subsections: Adenophylli, Caribaeus, Laceratoglandulosus, Meridionalis, Pungentes and Velamea. Croton subg. Adenophylli and its infracategories have been considered monophyletic, even though the sampling used to carry out phylogenetic studies comprises less than 40% of the species. The section Adenophylli includes taxa recognized by their habit subshrubby or shrubby with stellate trichomes, leaves with or without glands at the apex of the petiole, base and/or margin of the blade, inflorescences with unisexual cymules, usually pistillate flowers sessile or subsessile and fruit columella with three ascending appendages and usually ventrally inflated. Croton sect. Adenophylli repeats the distribution of its subgenus and although it is morphologically well delimited, it is one of the most complex and taxonomically understudied of the genus. In Brazil, the section Adenophylli is one of the most diverse of the genus, with about 50 species distributed from north to south of the country, recognized mainly from studies developed in the 19th century (e.g., Flora Brasiliensis) and often found in local herbaria without identification or mistakenly identified. This thesis had as main objectives: a) reconstruct phylogenies for C. subg. Adenophylli from a sampling that contemplates the morphological and habitat diversity of its species, in order to test its monophyly, and hat of its infracategories; b) determine the systematic position of species not placed in any of the subsections or sections of the subgenus Adenophylli; c) propose a classification for the Adenophylli subgenus based on the phylogenies obtained, and d) review the taxonomy of species from the section Adenophylli occurring in Brazil. Phylogenetic reconstructions were performed using Maximum Parsimony, Maximum Likelihood and Bayesian Analysis based on plastid (trnL-F) and nuclear (ITS 1+5.8S+ITS2) DNA sequences, while the review included collections and observations of the species in field, and studies of herborized collections and specialized literature. The results of the thesis are presented in the form of two chapters, the first of which deals with the phylogeny of Croton subg. Adenophylli, in which we sampled 119 species, we recovered most sections and subsections as monophyletic, the latter with expanded circumscriptions, and we propose Croton sect. Pulegiodorus and C. sect. Pycanthi to accommodate species without systematic position at level of section. The second chapter deals with the taxonomic review of the species of Croton section Adenophylli occurring in Brazil, for which 23 species are recognized, contrasted in a key, described in detail, illustrated in their morphological nuances, represented by images, mapped and commented on the geographic distribution, conservation status, environmental preferences, flowering and fruiting times, morphological relationships and taxonomic histories.
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Classificação, Crotoneae, Endemismo, Flora do Brasil, Taxonomia