Revisão do gênero Sirodotia (Batrachospermales, Rhodophyta)
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Data
2020-08-28
Autores
Rossignolo, Natalia Leocadio
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Gêneros da ordem das algas vermelhas de águas continentais, Batrachospermales, foram recentemente investigados usando evidências moleculares e morfológicas, mas o gênero Sirodotia ainda não havia sido revisado. O presente estudo teve como objetivos: inferir as relações filogenéticas das espécies dentro do gênero Sirodotia e com outros gêneros da ordem Batrachospermales; conhecer os limites de variação intra e interespecífica com base na análise de três marcadores moleculares: gene plastidial que codifica a subunidade grande da RuBisCO (rbcL), região de “barcode” do gene mitocondrial que codifica a subunidade 1 da citocromo c oxidase (COI-5P) e região de “barcode” do gene nuclear que codifica a subunidade grande do ribossomo (rDNA LSU); e avaliar os caracteres morfológicos de valor diagnóstico para a delimitação de espécies do gênero em âmbito mundial à luz dos novos dados moleculares. Foram analisadas 40 amostras de Sirodotia provenientes de várias regiões do mundo, incluindo África, Ásia, Australásia, América do Norte, América do Sul e Europa, além de espécimes-tipo de seis espécies. Análises filogenéticas concatenadas e de um único gene (rbcL, COI-5P e LSU) mostraram o gênero Sirodotia como grupo monofilético com alto suporte, evidenciando clados ou grupos bem definidos, com nítida repartição biogeográfica delimitando as espécies, além de alta divergência interespecífica (2,1-8,1% e 4,4-10,5%) e baixa variação intraespecífica (0- 2,4% e 0-3,8%) para rbcL e COI-5P, respectivamente. As análises das sequências de LSU revelaram valores de divergência interespecíficas menores (0,7-3,3%) do que as sequências de COI-5P indicando menor poder de resolução como “barcode”. Os caracteres morfológicos diagnósticos previamente utilizados para distinguir o gênero (carpogônio assimétrico com protuberância basal e carposporófito difuso com filamentos prostrados produzindo ramos eretos com carposporângios) foram confirmados neste estudo. Algumas espécies apresentaram padrão biogeográfico bem definido: S. delicatuliformis ocorrência no Brasil e Costa Rica, S. amazonica (regiões centro-oeste e norte do Brasil) e S. cryptica (centro-oeste do Brasil), S. assamica (nordeste da Índia), S. aquiloamericana (sul da América do Norte), S. huillensis (sul e sudeste da África) e S. kennedyi (centro-sul da África). Assim, distribuição geográfica pode ser usada como critério adicional para o reconhecimento dessas espécies. Os seguintes caracteres foram considerados diagnósticos para distinguir as espécies do gênero: número de células dos fascículos primários, arranjo dos espermatângios, parte do carpogônio que produz os filamentos gonimoblásticos e dimensões do carposporângio. Com base na combinação de dados moleculares, morfológicos e biogeográficos foram reconhecidas nove espécies, cinco já descritas (S. assamica, S. delicatula, S. huillensis, S. kennedyi e S. suecica) e quatro novas espécies propostas neste trabalho (S. amazonica, S. aquiloamericana, S. cryptica e S. delicatuliformis). Das espécies previamente consideradas taxonomicamente aceitas no gênero, três (S. cirrhosa, S. gardneri e S. huangshanensis) não puderam ser reavaliadas, pois os espécimes tipo não estavam disponíveis para análise e os caracteres utilizados não foram considerados taxonomicamente informativos; e quatro espécies foram sinonimizadas neste trabalho (S. segawae, S. sinica e S. yutakae com S. suecica; e S. ateleia com S. delicatula).
Genera of the freshwater red algal order Batrachospermales were recently investigated using molecular and morphological evidences, but the genus Sirodotia had not yet been revised. The goals of this study were: to infer the phylogenetic relationships of the species within the genus Sirodotia and with other genera of the order Batrachospermales; to ascertain the limits of intra and interspecific variation, based on the analysis of three molecular markers: the plastid gene that encodes the RuBisCO large subunit (rbcL), the barcode region of the mitochondrial gene that encodes cytochrome c oxidase subunit 1 (COI-5P) and the barcode region of the nuclear gene that encodes the large ribosome subunit (rDNA LSU); and to evaluate the morphological characters of diagnostic value for delimitation of species in the genus worldwide in the light of the new molecular data. Forty samples of Sirodotia from different regions of the world were analyzed, including Africa, Asia, Australasia, North America, South America and Europe, in addition to type specimens of six species. Concatenated and single gene analyses showed the genus Sirodotia as a monophyletic group with high support, showing well-defined clades or groups, with clear biogeographic distribution delimiting species, in addition to high interspecific divergence (2.1-7% and 4.4-10.5%) and low intraspecific variation (0-2.4% and 0- 3.8%) for rbcL and COI-5P, respectively. The analysis of the LSU sequences revealed lower interspecific divergence values (0.7-3.3%) than the COI-5P sequences (4.4- 10.5%) indicating lower resolution as a barcode marker. The diagnostic morphological characters previously used to distinguish the genus (asymmetric carpogonium with basal protuberance and diffuse carposporophyte with prostrate filaments producing erect branches with carposporangia) were confirmed in this study. Some species showed a well-defined biogeographic pattern: S. delicatuliformis occurring in Brazil and Costa Rica, S. amazonica (midwestern and northern Brazil), S. cryptica (midwestern Brazil), S. assamica (northeastern India), S. aquiloamericana (southern North America), S. huillensis (southern and southeastern Africa) and S. kennedyi (southcentral Africa). Thus, geographic distribution can be used as an additional criterion for the recognition of these species. The following characters were considered diagnostic to distinguish species in the genus: number of cells of the primary fascicles, arrangement of spermatangia, part of the carpogonium that produces the gonimoblastic filaments and dimensions of the carposporangia. On the basis of a combination of molecular, morphological and biogeographic data nine species were recognized, five already described (S. assamica, S. delicatula, S. huillensis, S. kennedyi and S. suecica) and four new species proposed in this work (S. amazonica, S. aquiloamericana, S. cryptica and S delicatuliformis). Among the remaining species taxonomically accepted in the genus, three (S. cirrhosa, S. gardneri and S. huangshanensis) could not be re-evaluated, because the type specimens were not available for analysis and the characters used were not considered taxonomically informative; and four species were synonymyzed in this study (S. segawae, S. sinica and S. yutakae with S. suecica; and S. ateleia with S. delicatula).
Genera of the freshwater red algal order Batrachospermales were recently investigated using molecular and morphological evidences, but the genus Sirodotia had not yet been revised. The goals of this study were: to infer the phylogenetic relationships of the species within the genus Sirodotia and with other genera of the order Batrachospermales; to ascertain the limits of intra and interspecific variation, based on the analysis of three molecular markers: the plastid gene that encodes the RuBisCO large subunit (rbcL), the barcode region of the mitochondrial gene that encodes cytochrome c oxidase subunit 1 (COI-5P) and the barcode region of the nuclear gene that encodes the large ribosome subunit (rDNA LSU); and to evaluate the morphological characters of diagnostic value for delimitation of species in the genus worldwide in the light of the new molecular data. Forty samples of Sirodotia from different regions of the world were analyzed, including Africa, Asia, Australasia, North America, South America and Europe, in addition to type specimens of six species. Concatenated and single gene analyses showed the genus Sirodotia as a monophyletic group with high support, showing well-defined clades or groups, with clear biogeographic distribution delimiting species, in addition to high interspecific divergence (2.1-7% and 4.4-10.5%) and low intraspecific variation (0-2.4% and 0- 3.8%) for rbcL and COI-5P, respectively. The analysis of the LSU sequences revealed lower interspecific divergence values (0.7-3.3%) than the COI-5P sequences (4.4- 10.5%) indicating lower resolution as a barcode marker. The diagnostic morphological characters previously used to distinguish the genus (asymmetric carpogonium with basal protuberance and diffuse carposporophyte with prostrate filaments producing erect branches with carposporangia) were confirmed in this study. Some species showed a well-defined biogeographic pattern: S. delicatuliformis occurring in Brazil and Costa Rica, S. amazonica (midwestern and northern Brazil), S. cryptica (midwestern Brazil), S. assamica (northeastern India), S. aquiloamericana (southern North America), S. huillensis (southern and southeastern Africa) and S. kennedyi (southcentral Africa). Thus, geographic distribution can be used as an additional criterion for the recognition of these species. The following characters were considered diagnostic to distinguish species in the genus: number of cells of the primary fascicles, arrangement of spermatangia, part of the carpogonium that produces the gonimoblastic filaments and dimensions of the carposporangia. On the basis of a combination of molecular, morphological and biogeographic data nine species were recognized, five already described (S. assamica, S. delicatula, S. huillensis, S. kennedyi and S. suecica) and four new species proposed in this work (S. amazonica, S. aquiloamericana, S. cryptica and S delicatuliformis). Among the remaining species taxonomically accepted in the genus, three (S. cirrhosa, S. gardneri and S. huangshanensis) could not be re-evaluated, because the type specimens were not available for analysis and the characters used were not considered taxonomically informative; and four species were synonymyzed in this study (S. segawae, S. sinica and S. yutakae with S. suecica; and S. ateleia with S. delicatula).
Descrição
Palavras-chave
Batrachospermales, COI-5P, LSU, rbcL, Sirodotia, Morfologia, Sistemática molecular, Molecular systematics, Morphology