Hoya undulata (Apocynaceae, Asclepiadoideae), a new myrmecophytic species from Borneo, and typification of H. darwinii

In this paper we document the discovery of a new Hoya species from Borneo, H. undulata S.Rahayu & Rodda.The leaves of the new species form domatia, specialised structures harbouring ants, previously only observed in Hoya mitrata Kerr and H. darwinii Loher.The corona is unique among Bornean Hoya species as its lobes develop two lateral hooked appendages, also present in H. griffithii Hook.f, a species from mainland Asia.A lectotype for Hoya darwinii is also selected.