Aristolochia crocea, a new species of Aristolochia subsection Pentandrae (Aristolochiaceae) from Guerrero, Mexico

Aristolochia crocea from Atlixtac, Guerrero, Mexico, is described and illustrated as a new species. It belongs to Aristolochia subsection Pentandrae, the most diverse group of the genus in Mexico, with 48 species. The species is distinguished by its saffron-colored (yellow-orange) limb when aged, pale yellow throat, and trilobate leaf blades with the middle lobe narrowly triangular to triangular, and rounded lateral lobes. It shares morphological similarities with Aristolochia nelsonii, A. variifolia, and A. versabilifolia, for having trilobate-shaped leaves, and with A. oaxacana for the yellowish limb color. A comparative table with the main features of A. crocea and its morphologically closest species is provided, as well as an identification key, photographs, and distribution map.