Taxonomic differentiation among Portulaca minensis (Portulacaceae) and its allies occurring within the Espinhaço Range, Brazil, based on macro and microcharacters

Portulaca minensis is a poorly known species of Portulacaceae, considered exclusive to the campo rupestre vegetation in Minas Gerais, Brazil. It shares morphological features with members of the Cryptopetala clade, composed of P. mucronata, P. cryptopetala, and P. hirsutissima. The purpose of this paper is to expand the knowledge about the taxonomy, distribution, and micromorphology of P. minensis, comparing it to its morphologically related species occurring in the Espinhaço Range, along Eastern Brazil. We analyzed specimens of this group in herbaria and in the field and gathered data on micromorphology of seeds surface and pollen grains using scanning electron microscopy. In addition, we also analyzed leaf anatomy using light microscopy for the first time to this species. Portulaca minensis can be distinguished from its allies within the P. hirsutissima complex by glabrous leaves and sepaloid (vs. pilose) and from P. mucronata, it differs by reddish sepaloid structures (vs. greenish). As this species showed leaf anatomy with intermediate metabolism C3–C4, we consider it as a probable member of the Cryptopetala clade. The pantocolpate pollen grains were similar to most Portulaca species (except the P. hirsutissima complex), but the slightly convex ornate seeds with par-dome type projections were considered diagnostic to P. minensis. We also indicate new localities of occurrence to P. minensis in the state of Bahia, expanding the species distribution toward the Northeastern region. This species is classified as endangered according to the IUCN criteria (EN B1 + b(i, ii, iii), with EOO = 3,557,978 km2 and AOO = 28,000 km2. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.