A new species of Dalechampia from southeastern Brazil, belonging to Dalechampia sect. Dioscoreifoliae, is described and illustrated here. Dalechampia margarethiae is a twining vine occurring exclusively in Espírito Santo state. Its pseudanthia are similar to those of D. peckoltiana and D. pentaphylla, but D. margarethiae differs in a set of important characters, including having cylindrical, down-curved style tips, staminate flowers at anthesis having unreflexed sepals with stamens born on unelongated columns, whitish floral resin, and simple, entire, cordate leaves.