ADDITIONS TO THE FLORA OF THE KAIJENDE HIGHLANDS , PAPUA NEW GUINEA : GLOCHIDION WELZENII ( EUPHORBIACEAE ) , A NEW SPECIES FROM THE PAIELA LIMESTONE

The New Guinea cordillera ranks with Costa Rica-Chocó, Atlantic Brazil, Andes Amazonia, and Northern Borneo, as one of the world’s five principal centres for tracheophyte diversification (Barthlott et al. 1996, 2005). Particularly on the Indonesian side, many districts in central New Guinea consist of uninhabited wilderness and are collectively the largest intact repository for plant life in Papuasia. As part of a long-term plan for documenting this resource, Conservation International and its partners are currently implementing a series of multidisciplinary surveys of the Dividing Ranges. The initiative straddles the Indonesia-Papua New Guinea (PNG) border, encompassing a floristic region suspected of harbouring large numbers of rare or undiscovered taxa. The 2005 Kaijende survey was the lead operation on the bi-national itinerary (see Richards 2007, for a comprehensive summary), and was immediately followed by the widely publicised Foja I Expedition to Irian Jaya. Two novelties in Euphorbiaceae were discovered during these initial explorations of poorly known environments (Takeuchi 2007), of which Glochidion welzenii is the first to be formally presented.


INTRODUCTION
The New Guinea cordillera ranks with Costa Rica-Chocó, Atlantic Brazil, Andes Amazonia, and Northern Borneo, as one of the world's five principal centres for tracheophyte diversification (Barthlott et al. 1996(Barthlott et al. , 2005)).Particularly on the Indonesian side, many districts in central New Guinea consist of uninhabited wilderness and are collectively the largest intact repository for plant life in Papuasia.

Glochidion
Distribution -Known only from the type locality in the Lake Tawa limestone district.
Etymology -Peter van Welzen (L) is an authority on the Euphorbiaceae and a frequent contributor to our knowledge of the Malesian flora.
Notes -1.Glochidion welzenii will key directly to couplet 21 (G.dumicola and G. oogynum) in Airy Shaw (1980: 95), but there are also apparent similarities with G. oblongifolium.The differentiating character states for these species are summarized in Table 1.
2. With microphyllous blades and retusely-notched trigonous fruits, Glochidion welzenii is reminiscent of Phyllanthus in aspect but is otherwise clearly a Glochidion.The novelty is easily distinguished from congeners by its small leaves and solitary flowers.Table 1.Compilation of differentiating characters for Glochidion welzenii and the species closest to it.The entries for Glochidion dumicola, G. oblongifolium, and G. oogynum were extracted from type descriptions and refined by examination of specimens cited by Airy Shaw (1980).4. The type locality is surrounded to the north and west by extensive Pandanus savannah of a type untreated in existing systems of vegetation classification (e.g., Paijmans 1976).These unusual formations are associated with the presence of clay hardpans on undulating tableland, where impeded drainage results in surface waterlogging.Glochidion welzenii is a prominent component of such areas and occurs primarily in its open habitats.

Glochidion oblongifolium
No evidence of fire influence was seen during the survey, consistent with the presumption of a natural origin for the savannah.The oftentimes sharp and regular border between savannah and forest (without the wind-shaped grassy 'fingers' characteristic of fire), is also suggestive of a non-anthropogenic status.In the current forest classification system for Papua New Guinea (Hammermaster & Saunders 1995a, b) the Paiela savannah is mapped as 'Gi' and 'Sc' (subalpine grassland and scrub, respectively) but is profoundly different in structure and composition from supposedly equivalent areas elsewhere in the Kaijende Highlands (e.g., in the Waile Creek-Omyaka district near Porgera).
5. Paiela is the largest remaining tract of uninhabited forest within the Highlands region.The need for long helicopter flights when accessing the interior has been largely responsible for the district's unexplored status.Several localities near Lake Tawa are distinguished by spectacular occurrences of doline karst (Löffler 1977), a landform characterized by impassable arrays of knife-ridge limestone.Despite the many discoveries made during the expedition, future exploration of this unique environment will be deterred by the difficulty and logistical costs of access.

Fig. 4 .
Fig. 4. Ground view of the Paiela savannah, principal habitat for Glochidion welzenii.The pandan communities are a previously-unrecorded vegetation facies.

Fig. 3 .
Fig. 3. Aerial perspective of the type locality at Lake Tawa. A. Pandanus savannah forms the lightcoloured vegetation on flat terrain.
Glochidion are disproportionately represented by large-leaved species with multilocular capsules (AiryShaw 1972).The depauperate taxa such as G. welzenii are much fewer in number and rarely collected.