Aristolochia binhthuanensis (Aristolochiaceae), a New Species and a Key to the Species of A. Subgen. Aristolochia in Vietnam

Abstract

Aristolochia binhthuanensis T.V. Do (Aristolochiaceae), a new species from southern Vietnam, is described and illustrated. It is characterized by a cordate to round leaf blade, 11–14 × 8–12 cm, glabrous on both surfaces, and palmately 9-nerved at base; cymes 2–3-flowered on inflorescence axes up to 5 mm long; broadly ovate bracteole, 7–12 × 4–6 mm; yellow perianth; sessile, oblong-ovate utricle, 8–13 × 5–8 mm; 1-lipped, sagittate limb with the upper part ovate-lanceolate, 12–16 × 7–9 mm, bent backward and with an acute apex; and 6-lobed gynostemium with conical apices. Based on morphology the new species is placed into Aristolochia subgenus Aristolochia series Aristolochia. A detailed description, notes on phenology, distribution and ecology as well as comparison with morphologically similar species are presented. An identification key to the Vietnamese species of Aristolochia subgenus Aristolochia is provided.