Content area
Full Text
(ProQuest: ... denotes non-US-ASCII text omitted.)
Introduction
Hoya R.Br. (Apocynaceae) is a monophyletic genus well rooted within Asclepiadoideae (Wanntorp et al., 2006). It was last revised in De Candolle's Prodromus (Decaisne, 1844) and is in urgent need of revision (Meve, 2002).
The International Plant Names Index lists more than 600 Hoya species names but estimates of the true number of species are extremely variable, ranging between 200 and 300 (Forster et al., 1998; Kleijn & Van Donkelaar, 2001). These are very conservative estimates and likely many more species are still undescribed.
Apart from the lack of a complete revision, the broad Indomalesian-Australian-Western Pacific distribution also makes an accurate estimate of the number of species difficult. The regions with the highest known species diversity are the Philippines and New Guinea but many parts of the distribution of the genus are still undercollected (Forster et al., 1998).
Chinese Hoya are rather better known because they have recently been revised for the Flora of China (Li et al., 1995) where 32 species and one variety of Hoya are recorded. With the recently published Hoya baishaensis Shao Y.He & P.T.Li (He et al., 2009a), H. bawanglingensis Shao Y.He & P.T.Li (He et al., 2009b) and H. persicinicoronaria Shao Y.He & P.T.Li (He et al., 2009c), the total number of Chinese Hoya species has been raised to 35. In these treatments Hoya yuennanensis was considered a synonym of H. lyi although neither species has been lectotypified. While searching for suitable lectotypes at the herbaria of B, BM, C, E, FI, GH, HBG, HITBC, IBSC, K, L, P, S, SING, TO, W, WRSL, WU and Z it became apparent that two separate morphological entities are present and, therefore, the name Hoya yuennanensis should be resurrected. It also became apparent that Hoya mekongensis (Gilbert et al., 1995) is morphologically indistinguishable from H. yuennanensis.
In the present paper I (i) discuss the taxonomic history of Hoya lyi and H. yuennanensis, (ii) emend their descriptions, (iii) lectotypify H. lyi and H. yuennanensis, (iv) resurrect the name H. yuennanensis, and (v) synonymise H. mekongensis with H. yuennanensis.
Taxonomic History and Current Study
In 1907, when Hoya lyi was published (Léveillé,...