Preliminary checklist of Hoya (Asclepiadaceae) in the flora of Cambodia, Laos and Vietnam

This paper provides new data on 33 new or rare species of Hoya obtained in fieldwork mainly during 2012–2017 in eastern Indochina including Cambodia, Laos and Vietnam. These data include illustrated descriptions of three species new for science, as well as illustrated records of 24 species new for the floras of the studied countries. When these new data are included, the flora of eastern Indochina comprises at least 45 species. Among them eight species are recorded and documented for Cambodia, 21 sp. for Laos and 40 sp. for Vietnam; two new species are described in Vietnam (H. crassipetiolata and H. nutans) and one species is described from Laos (H. uniflora). Eighteen species were recorded newly for the flora of Vietnam (H. arnottiana, H. burmanica, H. chinghungensis, H. erythrina, H. erythrostemma, H. fungii, H. griffithii, H. hainanensis, H. lanceolata, H. linearis, H. loyceandrewsiana, H. mengtzeensis, H. nummularioides, H. pachyclada, H. pandurata, H. parviflora, H. revolubilis, H. vaccinioides), nine for Laos (H. arnottiana, H. carnosa, H. chinghungensis, H. fungii, H. globulosa, H. griffithii, H. linearis, H. pandurata, H. polyneura) and two for Cambodia (H. lobbii, H. multiflora). New localities were discovered for H. bonii, H. lockii, H. lyi, H. micrantha, H. multiflora, H. oblongacutifolia, and H. verticillata known earlier in Cambodia, Laos and Vietnam by few collections. Lectotypes are proposed for the following eight species: H. arnottiana, H griffithii, H. lanceolata, H. lobbii, H. nummularioides, H. oblongacutifolia, H. pachyclada, and H. vaccinioides. Names of five taxa earlier known as separate species (H. villosa, H. pseudovalifolia, H. graveolens, H. balansae) are regarded as synonyms of H. globulosa, H. micrantha, H. oblongacutifolia, H. verticillata respectively.