StatuS of agathiS flaveScenS ( araucariaceae ) in PeninSular MalaySia

The narrowly endemic species Agathis flavescens Ridl., known only from altitudes between 1100 and 2100 m on Gunung Tahan and Gunung Rabong, Peninsular Malaysia, is reinstated as a distinct species.


INTRODUCTION
Agathis Salisb. is in Peninsular Malaysia represented by two species, A. flavescens Ridl.and A. borneensis Warb.Agathis flavescens, a montane species, is endemic on Gunung Tahan, the highest mountain in Peninsular Malaysia (2187 m) and nearby Gunung Rabong (1539 m).Ridley (1914) described it as new based on the size of the tree (< 21 m) and the small size of the male cone.Furthermore, he noted that it was conspicuous on exposed mountain ridges due to the "curious yellow colour" of the tree crown.Whitmore (1980) reduced it to subspecific rank as A. dammara (Lamb.)Rich.subsp.flavescens (Ridl.)Whitmore on the grounds that it is sympatric with A. borneensis and that the shape and size of the male cone and microsporophyll of the two taxa are not different (Whitmore, 1980).He stated that careful observations on Gunung Tahan are necessary to elucidate its status (Whitmore, 1972) and speculated that A. flavescens is a high mountain form of A. borneensis (Whitmore, 1980).Later, on nomenclatural grounds, Veldkamp & De Laubenfels (1984) transferred this subspecies to A. celebica (Koord.)Warb.subsp.flavescens (Ridl.)Veldkamp & Whitmore. De Laubenfels (1988), however, treated A. flavescens as a species distinct from A. borneensis based on a wider range of characters, namely size of leaf, size and shape of the male cone and microsporophyll and the type of the basal lobe of the megasporophyll, but he gave no reason for the change.Farjon (2001) listed it as a distinct species.
The aim of this study is to reassess the characters used to separate these two taxa based not only on herbarium specimens but also on field observations of populations of both species on Gunung Tahan.
In the statistical analysis, only Peninsular Malaysian specimens with vegetative and reproductive structures (8 A. flavescens and 13 A. borneensis) were selected.Character states of 9 characters (7 quantitative and 2 qualitative) were recorded from the specimens.

Each herbarium specimen was considered an individual Operational Taxonomic Unit (OTU). The computer program Multi-Variate Statistical Package (MVSP) version 3.10b
was used to test the significance of the combination of these characters.

Leaves
According to Whitmore (1980), the leaf is too variable and does not have any taxonomic value.De Laubenfels (1988) recorded a leaf size of 3-4 by 1-2 cm for A. flavescens and 6-12 by 2-3.5 cm for A. borneensis.However, I found that although the figures for absolute length and width overlap, 3-5.5(-5.9)by (1-)2.5-3cm for A. flavescens and (4-)7.2-11.3(-14.5)by (2-)2.5-4(-5.5)cm for A. borneensis, the ratio of width to length effectively separates these two taxa.Agathis flavescens has an average ratio of 2.16 while that for A. borneensis is 3.10.In addition, the leaf apex of A. flavescens is rounded while that of the majority of A. borneensis is pointed.
Field examination confirm Ridley's 1914 observation that in totally exposed habitats, leaves of A. flavescens are distinctly glossy yellow, while in more shaded habitats, they are yellowish green.In contrast, those of A. borneensis are always dark glossy green.
Furthermore, field observations and herbarium specimens showed that a pair of leaflike bracts below the cone of A. flavescens is a constant character that is not seen in A. borneensis.This important character was not mentioned by De Laubenfels (1988).

Female cones and megasporophylls
De Laubenfels (1988) distinguished the taxa by the presence and shape of the lobes at the base of the megasporophyll: Agathis flavescens has two rounded lobes while A. borneensis has only a sharply angled lobe.However, based on the specimens collected from the field, this character is neither consistent nor distinct (Fig. 1) because the shape and size of the megasporophyll differ greatly in a single cone depending on its position within the cone.

Habitat
Two populations of A. flavescens were studied on Gunung Tahan: one on the northwest side at 1500 m (near Berlumut Camp,4° 38' 24.6" N,102° 11' 47.6" E) and the other on the south side at 1633 m (near Gunung Reskit 4° 35' 52.5" N,102° 15' 29.3" E).Agathis borneensis grows on the north-west side at 698 m (Kor Camp, 4° 39' 05.5" N, 102° 10' 34.7" E) and at 1099 m on the south side near Pondok Dua Belas Camp (4° 34' 28.7" N, 102° 16' 39.7" E) and at 575 m on Gunung Rajah (4° 30' 28.4" N, 102° 21' 16.2" E).Although they are reported as sympatric on Gunung Tahan, the populations of the two taxa do not actually overlap but are separated by altitude.Agathis flavescens is found at the altitude above 1500 m while A. borneensis is found below 1100 m.Ridley's observation that A. flavescens is a smaller tree is correct, it grows up to about 21 m in height while A. borneensis can reach 50 m.

CONCLUSIONS
In addition to the characters used by De Laubenfels (1988) (namely a combination of leaf size, leaf apex, shape and size of the male cone and microsporophyll), the pair of bracts below the male cone, tree height and their altitudinal range are also important characters to distinguish the two taxa.Analysis using MVSP show conclusively that A. flavescens is clearly distinguished from A. borneensis by combination of these characters (Fig. 2).However, characters of the megasporophyll are not useful.Therefore, A. flavescens warrants species status.Fig. 2. Differentiation of Agathis flavescens Ridl.and A. borneensis Warb.using Principal Coordinates analysis using Pco case scores (Gower General Similarity Coefficient).Characters included in the analysis: Leaf (apex, length and width), male cone (length and width), microsporophyll (length), microsporophyll head (shape, length and width).