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| Mimosa baptistae Schmidt-Silveira & Miotto, in Silveira, de Vargas, Fortuna-Perez & Miotto, 2019. |
ABSTRACT
Mimosa baptistae is a new species presenting stalked glandular trichomes that give it a glutinous appearance, mainly with respect to the leaflets. Furthermore, it is an aculeate species, with multijugate leaves, white stamens, and fruits also covered by glandular trichomes. A herbaria survey and fieldwork only recorded this species as occurring on sandstone outcrops of the city Caçapava do Sul, Brazil. The species may be confused with other species of Mimosa sect. Batocaulon ser. Stipellares such as M. bifurca, M. sobralii and M. lepidota. However, features such as absence/presence of aculei, stamens color, habitat, and flower features are useful for distinguishing them from the new species. Here, we provide notes on morphology, geographic distribution, as well as anatomical detail of its glandular trichomes and content. Finally, we discussed the taxonomic significance of the micromorphology of glandular trichomes and their content in Mimosa ser. Stipellares as well as the potential applicability of such features to better understand the morphology of this series.
Keywords: glands; leaflets; Pampa; secretory structures; Serra do Sudeste
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| Figure 1: Mimosa baptistae: A. Habitat at Serra do Sudeste, Pampa biome, Brazil. B. Detail of a shrub individual; C. Population density. D. Arrangement of inflorescence, also showing the white stamens. E. Fruits. F. Detail of branches covered by a colorless and bright substance, resembling a resin. (Photos B and D from G.P. Coelho; Photos A, C, E, F from F. Schmidt-Silveira). |
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| Figure 2: Mimosa baptistae morphological details. A. Capituliform subglobose inflorescence B. Leaflets C. Aculei. D. leaflets punctuations E. Subquadrangular branches with grooves. F. Calyx and corolla G. Fruit. H. Articles covered by a colorless and bright substance, resembling a resin. Scale bars of 1mm. (A-H from the holotype, photo A from G. P. Coelho; photos B-H from F. Schmidt-Silveira). |
Mimosa baptistae Schmidt-Silveira & Miotto sp. nov .
Distribution and ecology: Mimosa baptistae may be considered an endemic species up to now for Caçapava do Sul at the hills of Pedra do Segredo, Pedra do Leão and their neighborhood, in Serra do Sudeste (Rio Grande do Sul State), where it grows on sandstone outcrops, shrublands (vassoural), and rocky grasslands, at approximately 200 to 500 m elevation. Caçapava do Sul belongs to the physiographic region of Serra do Sudeste (Fortes 1959), which is highlighted as a high-level priority area for conservation (CNCFlora 2014) in the Pampa biome. Furthermore, Pedra do Segredo and Pedra do Leão harbor other species endemic and rare such as Pavonia secreta Grings & Krapov, Petunia secreta Stehmann & Semir, Petunia exserta Stehmann, and Croton pygmaeus L.R. Lima (Grings et al. 2011).
Etymology: The specific epithet is in honor of Dr. Luís Rios de Moura Baptista, who studied many groups of plants from the Flora of Rio Grande do Sul, including the Mimosa genus.
Fernanda Schmidt Silveira, Wanderleia de Vargas, Ana Paula Fortuna-Perez and Silvia Teresinha Sfoggia Miotto. 2019. A New Glandular Mimosa Species from Southern Brazil and Insights About Its Glandular Trichomes Micromorphology. Acta Bot. Bras. 33(4); DOI: 10.1590/0102-33062019abb0112
