Hoya thuhae (Apocynaceae, Asclepiadoideae), a new species and H. lobbii, new record for Vietnam

A new species, Hoya thuhae (Apocynaceae, Asclepiadoideae), from lowland areas of central Vietnam, is described. It resembles H. kerrii but may be distinguished by its finely pubescent petioles, puberulous leaf blade, longer peduncle, longer pilose to strigose pedicels, different shape of the calyx lobes, and elliptic corolla segments with apices raised above the central portion. Additionally, H. lobbii, known earlier in NE India, Thailand, and Cambodia, is recorded for Vietnam at first. Data on the ecology, phenology, distribution, and conservation status for both species are provided, together with plates compiled from original color analytical photos.