Ridleyandra chuana (Gesneriaceae), a new species from Peninsular Malaysia

Abstract Ridleyandra chuana, a new species of Gesneriaceae, is described and illustrated. It is endemic in Peninsular Malaysia and known from two small and restricted populations in montane forest. Its conservation status is assessed as vulnerable.


Introduction
Th is species was fi rst encountered in 1932 at Fraser's Hill, Pahang. However, it was only in 1999 when another population was discovered by L.S.L. Chua on Gunung Ulu Kali, Pahang, that suffi cient material was available for its description. Since then both these localities have been revisited and the Gunung Ulu Kali population is now the focus of conservation. Th is species is unusual in Ridleyandra in occupying a very narrow niche, which probably contributes to its rarity and small population size. Th is is clearly seen at the Fraser's Hill locality where a small population of less than 30 plants is confi ned to a small area where moss-covered granite rock just emerges above the soil surface but is absent from the surrounded area of soil where Codonoboea curtisii (Ridl.) C.L.Lim (Gesneriaceae) is plentiful.
It is a distinctive species among Ridleyandra species in its mammillate leaf surface with hairs on raised conical bases. Indeed, when sterile with its dark green leaves it more resembles Codonoboea crinita (Jack) C.L.Lim than R . atrocyanea (Ridl.) A.Weber, the only other Ridleyandra species with a mammillate leaf surface. Two species, R. kelantanensis Kiew and R. longisepala (Ridl.) A.Weber, have similar white corollas with purple lines and toothed leaves. In fact Weber (1998) listed Corner's Fraser's Hill specimens under R. longisepala but it is diff erent from this species that has bracts immediately below the sepals, longer petioles and sepals. It more resembles R. kelantanensis in their shorter petioles and sepals.
Ecology. On moss-covered granite rock embedded in soil or on low moss-covered granite boulders, in extremely damp, deeply shaded conditions on steep slopes in valleys. One population occurs in lower montane forest at 1250 m and the other in upper montane forest at-1570 m.
Etymology. Named in honour of Dr Lillian Swee Lian Chua, botanist and conservationist, who fi rst discovered this species on Gunung Kali while making an ecological inventory of the summit fl ora (Chua and Saw 2001).
Conservation status. EN B2ab(ii,iii). Following the 2001 IUCN Red List Categories and Criteria, (IUCN, 2001) this species is assessed as Endangered because it is known from two localities, one of which is threatened and only 130 known individuals. Th e population at Fraser's Hill falls within a Totally Protected Area (Chua 2010) and consists of about 30 plants that grow in an undisturbed site away from tourist trails and is too remote to be aff ected by development. Th e other population consists of less than 100 plants at Gunung Ulu Kali, which is on private land in a hill resort that is severely threatened by road widening and associated landslips, by changes in microclimate due to edge eff ect as the forest becomes more and more fragmented and from and that is in danger of encroachment from future development. Discussion. Plants in both populations are identical in all characters except for sepal length (6.5-7.5 mm in the Ulu Kali population and ca. 4 mm in the Fraser's Hill population).
In both the original collections (Chua FRI 40758 and Corner s.n. 1932) only a single fl owering specimen was collected suggesting that this is not a free-fl owering species. Monitoring over a longer period by JPC Tan suggests that there is a low level of fl owering throughout the year with periodic bursts of more intense fl owering. Th is same pattern is seen in some species of Codonoboea , such as C. platypus (C.B.Clarke) C.L.Lim (Kiew 2009b).