Mitteilungen des Kärntner Botanikzentrums Klagenfurt 189 Wulfenia 22 (2015): 189 –199 Review of the genus Plocoglottis (Orchidaceae) in Cambodia, Laos and Vietnam Maxim S. Nuraliev, Leonid V. Averyanov, Andrey N. Kuznetsov & Svetlana P. Kuznetsova Summary: The genus Plocoglottis is represented in Cambodia, Laos and Vietnam by three species. Plocoglottis bokorensis is known from several localities scattered within these three countries. Plocoglottis javanica and P. quadrifolia are presently found each in two localities in Southern Vietnam, being widely distributed in the Malesian region. The latter species is reported here for Cambodia, Laos and Vietnam for the first time with both of its Vietnamese populations located about 1000 km away from the nearest previously known collection. Details of distribution, illustrations and an identification key for these species are provided. Keywords: Plocoglottis, Indochina, flora, nature conservation, plant diversity, plant taxonomy The genus Plocoglottis Blume (Orchidaceae) comprises 40 – 45 species distributed in Malesia, Thailand, Eastern Indochina, Solomon and Andaman Islands as well as Peninsular Myanmar (Seidenfaden 1972, 1986, 1992; Seidenfaden & Wood 1992; Schuiteman & De Vogel 2000; Pridgeon et al. 2005; Schuiteman et al. 2008; Chong et al. 2009; Kurzweil 2009; Averyanov 2013a, b). The most recent accounts (Govaerts 2014; Chase et al. 2015) accept 41 species of Plocoglottis. This genus is currently placed within tribe Collabieae of subfamily Epidendroideae (Chase et al. 2015). Most of the species of Plocoglottis occur in the Malesian biogeographic region sensu Takhtajan (1986) (Pridgeon et al. 2005; Kurzweil 2009). In respect to continental Asia, five species are known from Thailand and the genus is also believed to occur in Southern Myanmar (Kurzweil 2009). In Vietnam, two species of Plocoglottis have been reported to date, namely P. bokorensis (Gagnep.) Seidenf. and P. javanica Blume (Averyanov 2002, 2013b; Averyanov & Averyanova 2003). For both Cambodia (Seidenfaden 1992; Schuiteman & De Vogel 2000) and Laos (Schuiteman et al. 2008; Averyanov 2013a) only one species, P. bokorensis, is known. The diversity of Plocoglottis in Thailand fully covers that of the other continental Asia areas. During the past decades, the knowledge of distribution area of Plocoglottis within continental Asia has been greatly improved. For instance, it was recently found for the first time in Northern Thailand (Kurzweil 2009). This genus has been supposed to be absent from Vietnam and Laos till recent years and it is not included in the appropriate regional accounts published before 2003 and 2008 respectively (Seidenfaden 1992; Pham Hoang Ho 2000; Schuiteman & De Vogel 2000; Nguyen Tien Ban et al. 2005; Newman et al. 2007). Here we provide an account of the genus Plocoglottis in Cambodia, Laos and Vietnam with a report of one more newly discovered species of this genus in the flora of Eastern Indochina. A population of Plocoglottis quadrifolia J.J. Sm. was found in late May 2014 in the mountains of Southern Vietnam, in Chu Yang Sin National Park. The population consisted of more than ten © Landesmuseum für Kärnten; download www.landesmuseum.ktn.gv.at/wulfenia; www.zobodat.at