A new species of Pleroma (Melastomataceae) from the Southern Espinhaço, Minas Gerais, Brazil

From Firenze University Press Journal: Journal of Plant Taxonomy and Geography (Webbia)

Paulo José Fernandes Guimaraes, Diretoria de Pesquisa Científica, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro

Diego Nunes Da Silva, Diretoria de Pesquisa Científica, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro

Inara Montini Araújo, Instituto de Biologia, Universidade Federal de Uberlândia

Rosana Romero, Instituto de Biologia, Universidade Federal de Uberlândia

Pleroma is a Neotropical genus of the tribe Melastomateae whose morphological characteristics are the extension of the connective beyond the thecae called pedoconnective, ovary apex with a persistent crown of erect tri-chomes surrounding the base of the style and cochleate seeds (Renner 1993; Guimarães et al. 2019; Veranso-Libalah et al. 2022).

In Brazil there are 159 species of Pleroma distributed mainly in the Atlantic Forest with 105 species and Cerrado with 58 species, of which 4 are shared between these biomes (Guimarães 2022). The main features of Pleroma are the shrubby habit, rarely arboreal or herbaceous, flowers with 5 petals, purple to lilac or rarely white, anthers purple or pink, filaments with the frequent presence of trichomes capitate-glandular, and deciduous sepals that are absent on hypanthia that envelop mature capsules (Guimarães et al. 2019).

The Espinhaço Range is a major center of plant diversity in eastern Brazil (Giulietti and Pirani 1988; Giulietti et al. 1997; Colli-Silva et al. 2019) that extends for more than 1200 km along the states of Bahia and Minas Gerais (Almeida-Abreu and Renger 2002), with a predominance of campo rupestre vegetation (Vasconce-los 2011; Alves et al. 2014). This imposing mountainous expanse is composed mainly of herbaceous, subshrubby and shrubby life forms (Colli-Silva et al. 2019), origi-nating from the Cerrado, Caatinga and Atlantic For-est (Conceição et al. 2016), and can be divided into two physiographic domains known as Chapada da Diaman-tina (comprising the northern portion, in the state of Bahia) and Serra do Espinhaço (southern portion, Minas Gerais) (Danderfer and Dardenne 2002; Gontijo 2008). These domains were recognized and characterized by Colli-Silva et al. (2019), respectively, as Chapada da Dia-mantina and Southern Espinhaço provinces.

Following the classification by Colli-Silva et al. (2019), the Southern Espinhaço is subdivided into three districts: Grão-Mog-ol, Diamantina Plateau, and Iron Quadrangle.In the Southern Espinhaço, Melastomataceae stand out as one of the vascular plant families with the most endemic species in the province (Colli-Silva et al. 2019). While in Grão-Mogol and Diamantina Plateau districts, the family is one of the richest [e.g., Pirani et al. (2003, 2015); see also Paranhos (2020) for an updated list of Melastomataceae from the Diamantina Plateau]. However, the richness of the family in Grão-Mogol and Diamantina Plateau has increased significantly with 46 new species being described in the last 10 years (Supplemen-tary file).

Futhermore, floristic studies have contributed to the review of species occurrence and diversity within the provinces (e.g., Candido 2005; Martins et al. 2009; Araújo 2013; Paranhos 2020).During a f loristic study focused on Melastoma-taceae from Biribiri State Park, in the state of Minas Gerais (Araújo 2013), an enigmatic species of Pleroma was found, but initially identified as Pleroma formosum(Cogn.) P.J.F.Guim. & Michelang. When we examined specimens more closely, we confirmed that it is a new species endemic to the Southern Espinhaço, occurring in the Diamantina Plateau and Grão-Mogol districts, Minas Gerais, Brazil. We here describe, illustrate and compare this new species to morphologically similar species. In addition, notes on its geographic distribution and conservation status, photos of living specimens, and scanning electron microscopy (SEM) images are provided.

DOI: https://doi.org/10.36253/jopt-13088

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