Two new endemic species of Portulaca (Portulacaceae) from the Brazilian Pampa grasslands

Portulaca L. is a monophyletic, cosmopolitan genus of succulent plants comprising ca 153 species, with particularly high diversity in xerophytic ecosystems in tropical and subtropical regions. Based on morphological evidence, we describe and illustrate two new species from the Brazilian Pampa, Portulaca guaritensis and Portulaca guenoa . The descriptions are accompanied by photographs, a line drawing, and notes on taxonomy, phenology, distribution, habitat, conservation status, and etymology. In addition, we provide an identification key to the species of Portulaca found in the Brazilian Pampa grasslands. The new species are distinguished from closely related taxa by a combination of vegetative and reproductive characters, including root morphology, leaf blade shape, number of involucral leaves, petal length and color, stamen number and color, stigma shape, and capsule morphology. These discoveries increase the number of Portulaca species recorded for Brazil to 25 and reinforce the need for fieldwork in the Pampa grasslands, which are increasingly threatened by rapid land‐use change.