A review of dipterocarps - Center for International Forestry Research

Biogeography and Evolutionary Systematics of Dipterocarpaceae
Present Distribution in the Phytogeographical
Regions
The South American region possesses now two
monospecific genera related to Dipterocarpaceae sensu
lato, and belonging to the two different non-Asian main
groups: Pseudomonotes attributed by its authors to
Monotoideae, and Pakaraimaea in Pakaraimoideae
sensu Maguire et al. (1977).
Pseudomonotes tropenbosii appears to be confined
to a small area in the southwesternmost limit of the
Guyana Highland and the superposed Roraima Formation
sediments in Amazonian Colombia (Fig. 1: nov. gen.). In
spite of being found near the distribution area of
Pakaraimaea, Pseudomonotes has stronger affinities
with the African species. Such affinities recall the remote
Gondwanan connection between Africa and South
America.
Pakaraimaea dipterocarpacea contains two
subspecies: P. dipterocarpacea ssp. dipterocarpacea in
Imbaimadai savannas, Pakaraima Mountains, Guyana, and
P. dipterocarpacea ssp. nitida in Gran Sabana and
Guaiquinima, Venezuela (Maguire and Steyermark
1981). The new genus Pseudomonotes from Colombia
(Fig. 1) in most respects seems to be a Monotoideae
(sensu Maguire and Ashton in Maguire et al. 1977), not
a Pakaraimoideae (Londoño et al. 1995).
African dipterocarps need a reassessment to reduce
over-estimations in the Angolan flora. All Monotes
(about 26 instead of 32 (Verdcourt 1989)) and
Marquesia (3 or 4 species) grow in the southern
hemisphere. Only Monotes kerstingii occurs in both
hemispheres (Fig. 1). It occurs in the northern
hemisphere as an isolated species in a narrow strip, and
in the southern hemisphere in the main distribution area
of the Monoitoideae. Some species exist through
Katanga, Zambia and Mozambique up to the Indian Ocean.
Only one species (Monotes madagascariensis) reaches
south Madagascar.
Marquesia may form monospecific open forests
along the fringe of the Congolese rain forest, at the limit
of Zaire, Angola and northern Zambia.
The numbers of genera and species in Asia (Table 4:
* indicates Ashton’s 1982 numbers) show much greater
diversity compared to Africa and South America. As
expected the higher numbers clearly occur in the everwet
regions. The same trend exists from the Malesian region
(10 or 14 genera, 465* species) and particularly from
Borneo (13 genera, 267* species) and Peninsular
14
Malaysia (14 genera, 155* species), westwards to
mainland southeast Asia (8 genera, 76 species) to Sri
Lanka (7 or 9 genera, 44-58 species), India (5 or 6 genera,
31 species) and the Seychelles (1 genus, 1 species). The
same situation appears eastwards inside the Malesian
region from Borneo to Peninsular Malaysia or to the
Philippines (11 genera, 50* species) and from Malesia
to China (5 genera, 11 or 24 species). The number of
taxa strongly decrease on the east side of the Wallace’s
line in the Philippines (3/11* genera, 13/50* species)
and New Guinea (3* genera, 15* species).
Particular needs for a new synthesis concern the
Chinese taxa (Yunnan, South China, Hainan Island), using
both the published literature (Wang et al. 1981, Tao and
Tong 1982, Tao and Zhang 1983, Tao and Dunaiqiu 1984,
Huang 1987, Zhu and Wang 1992), the on-going works
(Yang Yong Kang 1994 personnal communication) and
new collections to be done. Dipterocarps in New Guinea
and the Philippines have been identified (Revilla 1976)
but some biological aspects have to be specified.
Cotylelobium Pierre and Pentacme, are the only
Asian dipterocarps with a present disjunct distribution
area (Table 5). Cotylelobium grows in Sri Lanka,
mainland Southeast Asia and Sundaland, both under
seasonal and aseasonal evergreen forests. Pentacme
develops in mainland Southeast Asia and also in the
Philippines and Papua-New Guinea. Only five genera
develop east of Wallace’s line (Ashton 1979a) if
Pentacme is not merged into Shorea genus:
Dipterocarpus, Vatica (including Sunaptea), Hopea
(section Hopeae) and Shorea (Anthoshorea and
Brachypterae groups) and Pentacme. Apart from
Pentacme, the other four genera presently exist in India
and occur in Indian fossils (Table 5) as does the genus
Anisoptera (presently extinct). Anthoshorea Heim
extends from India to east of Wallace’s line. Section
Shorea Ashton is mainly centered in southeast Asia but
is well represented in Sri Lanka; it contains two fireresistant
species in the Indian and Indo-Burmese dry
dipterocarp forests. The other genera or sections have
more restricted areas (Table 5). The south Asian endemic
taxa are Vateria genus represented in south India and Sri
Lanka, and Stemonoporus and Doona confined to Sri
Lanka. In the southeast part Upuna is endemic in Borneo.
Two genera, Vatica (sensu Kostermans) and Hopea,
show the largest distribution from India to east of
Wallace’s line. This is an important fact.