Heterostemma pingtaoi (Apocynaceae, Asclepiadoideae), a New Species from Hainan, China

Heterostemma pingtaoi S. Y. He & J. Y. Lin (Apocynaceae, Aselepiadoideae) is described from Hainan Province, China. The new species is morphologically similar to H. oblongifolium Costantin in its leaf blade with an acute apex and rounded base. In comparison, H. pingtaoi differs from H. oblongiflium in its pubescent petioles (vs. glabrous), 1110 leaves only to 7.3 cm long (vs. 7.5.14 cm), the five calyx glands (vs. 10), and the corolla externally pubescent and yellow-green with mauve pubescence (vs. green and glabrous).