Two new species of Hoya R.Br. (Apocynaceae, Asclepiadoideae) from Borneo

Two new Hoya R.Br. species from Borneo are described and illustrated. The first, Hoya ruthiae Rodda was collected in Sabah on Bukit Baturong, a limestone outcrop. It is one of the few species in the genus to have clear exudate. It is compared with the morphologically related Hoya uncinata Teijsm. and Binn. The other, Hoya bakoensis Rodda, was collected in the kerangas forests of Bako National Park. It belongs to Hoya section Acanthostemma (Bl.) Kloppenb., a section with numerous members in the Philippines but under-represented in Borneo.