Pollen morphology: a source of information for taxonomic studies within Campomanesia (Myrtaceae)

Abstract

Campomanesia is a well-delimited Neotropical genus of Myrtaceae, but some of its species have a poorly understood circumscription. Pollen morphology can provide characters to clarify the relationships among such taxa. Here, we analyze the pollen grains of 16 species of Campomanesia using light and scanning electron microscopy. Heat map and multivariate regression tree analyses were performed aiming to detect differences among species based on pollen morphology. Pollen grains of the studied taxa are isopolar monads that are oblate or, less often, suboblate, 3(4)-colporate, syncolporate or parasyncolporate, with a triangular or quandrangular amb. The exine ornamentation varies among rugulate-granulate, granulate, rugulate and rugulate-espiculate. Fastigium is present in 14 species, and a costa is present in three species. The heat map and regression tree analyses based on 16 character states of pollen morphology were able to distinguish all species of Campomanesia studied here. Some species differ from all the other species, such as Campomanesia guaviroba due to its exclusively rugulate exine. Amb, shape and exine ornamentation were distinctive characters, as previously reported for other genera of Myrtaceae. However, the presence of fastigium also proved to be an informative pollen character for species distinction in Campomanesia. Based on the sample of this study, we can state that Campomanesia is a eurypalynous genus within Myrtaceae.

Keywords:

• Myrteae
• Neotropical
• Pimenta
• taxonomy

Acknowledgements

JL is grateful to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for a doctoral fellowship. VGE, CBFM and TTC are grateful to the CNPq for ‘Bolsa de Produtividade em Pesquisa’ research fellowships. VGE is also grateful to the CNPq for the research grant ‘Chamada Universal 2018’. TTC and JL are grateful to the Fundação de Amparo à Pesquisa e Inovação do Espírito Santo (FAPES) for the research grant ‘Taxa de Pesquisa’ and for the master’s fellowship, respectively. VGE is grateful to Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro for the funding ‘Auxílio Emergencial ao Museu Nacional, FAPERJ’ (#200.090/2019).

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq): ‘Bolsa de Produtividade em Pesquisa’ for TTC (#310458/2019-6), CBFM (#311618/2021-9), and VGE (#304910/2019-8); ‘Chamada Universal 2018’ (#422903/2018-3) for VGE. Fundação de Amparo à Pesquisa e Inovação do Espírito Santo (FAPES): “Taxa de Pesquisa” (#297/2021) for TT Carrijo, and for the Master's course scholarship to JL. Coordernação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) – Finance Code 001 to JL.