A new species of Hoya R.Br. from Tam Đảo National Park (Vĩnh Phúc Province, Vietnam), Hoya tamdaoensis Rodda & T.B.Tran,is described and illustrated. It is distinguished from the morphologically similar Hoya siamica Craib by corolla size, lamina shape, coloration, and orientation of the petioles.
Keywords: Hoya siamica, limestone, lithophytic, lower montane forest, Marsdenieae, Eudicots, Vietnam
Hoya tamdaoensis Rodda & T.B.Tran spec. nov. (Figs. 1 & 2) Similar to Hoya siamica Craib (1910: 419) in exhibiting inflorescences positively geotropic, convex, flowers numerous, corollas white, pubescent within, and leaves glabrous, but distinguished by the corolla size (1.8–2.2 cm diam. vs. < 1 cm diam. in H. siamica) and the lamina shape (base attenuate-rounded and apex caudate vs. base cuneate or acute and apex acute or acuminate in H. siamica).
TYPE:— VIETNAM, Vĩnh Phúc prov., Tam Đảo N.P., Máy Giấy trail, 1072 m, 20 September 2011, Nguyễn Quốc Bình, Jana Leong- Škorničková, Trần Hữu Đăng VNM-B1465 (holotype, SING!; isotypes HN!, VNMN!).
Etymology:— The new species is named after the collection locality, Tam Đảo National Park, Vietnam.
Distribution and ecology:— Only known from the type locality in Tam Đảo National Park, Vietnam. Hoya tamdaoensis was found growing epilithically on limestone covered by moss in evergreen lower montane forest.
Conservation status:— Known from only one locality; the preliminary conservation status of Hoya tamdaoensis is Data Deficient (DD; IUCN 2014).
Michele Rodda, The Bach Tran and Quoc Binh Nguyen. 2015. Hoya tamdaoensis (Apocynaceae, Asclepiadoideae), A New Species from Vietnam. Phytotaxa. 217(3): 288–292. DOI: 10.11646/phytotaxa.217.3.6