A new species of Aeschynomene (Papilionoideae: Dalbergieae) from Oaxaca, Mexico

Aeschynomene sousae Rudd ex A. Delgado et Sotuyo is described from southern Oaxaca, Mexico, where it is likely endemic to the northeast mountains of the Isthmus of Tehuantepec. It is a member of series Scopariae of subgenus Ochopodium, and morphologically similar to A. nicaraguensis from which it differs mainly in having ovate to lanceolate, larger bracteoles, bright yellow flowers with a reddish arched, insect guide-mark on the interior face of the standard petal, in the fusion of the 2 wing petals along part of their upper margins and also fruits bearing 1 to 2 seeds.