Rhododendron chamahensis ( Ericaceae ) , a new species from Peninsular Malaysia

Rhododendron chamahensis Rafidah, sp. nov., an epiphytic shrub from Gunung Chamah, Kelantan, Malaysia, is described and illustrated.


INTRODUCTION
As part of the botanical exploration programme of the Flora of Peninsular Malaysia project (Kiew & Rafidah 2007), an expedition was organized to Gunung Chamah because the east side of the Main Range, a very biodiverse area, is poorly known botanically.Gunung Chamah lies in the south-western corner of Kelantan and is the fifth highest mountain in Peninsular Malaysia with an elevation of 2 171 m.During the expedition, the team collected three species of Rhododendron, R. malayanum Jack and R. wrayi King that were common, and the new species.
Accounts for Rhododendron in Peninsular Malaysia include those by Sleumer (1966), Dransfield et al. (1978), Ng (1978), Soepadmo (2002) and Argent (2006).The last Rhododendron from Peninsular Malaysia to be described as new was R. sei mundii J.J.Sm.from Gunung Tahan, Pahang, described in 1935.With their big, showy flowers rhododendrons are relatively wellcollected so it is surprising that after a gap of 75 years a new rhododendron is discovered.
The new species is most similar to R. seimundii in its leaf shape, white, rotate-campanulate shaped flowers and corolla lobe shape, but it is different from this species by a combination of characters listed in Table 1.While the difference in leaf size may be attributed to differences in habitat -R.sei mundii grows in shallow soil in exposed conditions compared with the moist shaded condition where the new species grows -characters, such as its leaves being four times longer than broad, the tip of the leaf apex without a protruding gland, the rounded bracts, the longer pedicel, and the densely hairy ovary confirm that it is a distinct new species.The new species is also similar to R. lanceolatum Ridl.from Borneo by having white flowers and a hairy ovary but it is different in its much larger leaf (7-12 by 2.5 -4.5 cm).
In addition, in its lower montane habitat R. chamahensis is unusual among Peninsular Malaysian rhododendrons that are mostly species of the upper montane ericaceous forest, although one or two are lowland species.
By having sessile scales, lobed entire, the centre not darkcoloured (Plate 1), rotate-campanulate corolla and the stamina filaments hairy from the base, the new species belongs to sec-tion Schisanthe Schltr.subsect.Euvireya H.F.Copel.(Craven et al. 2011).However, its subsectional position need to be confirmed when fruits and seeds become available.
Etymology.The epithet refers to the locality, Gunung Chamah.
Ecology -A rare species collected from the lower montane forest at altitudes of 1200 -1700 m (not from the peak) growing as an epiphytic shrub collected from a fallen tree by the river.

Table 1
Characters that distinguish R. chamahensis from R. seimundii.