Disjunctive patterns of Malesian mosses
235
Noteworthy disjunctive patterns of Malesian mosses
Benito C. Tan
Farlow Herbarium, HUH, Harvard University, 22 Divinity Avenue, Cambridge, MA 02138, USA
Key words: Malesian mosses, disjunction, plate tectonics, dispersal
Abstract
A review of some noteworthy patterns of disjunction of
Malesian moss distributions is presented. Correlation with
new information from the plate tectonic history of the
Malesian region offers a new interpretation of the origin and
migration of Malesian mosses. Although long distance and
chance dispersal remain important explanations for local
plant distribution patterns, it appears that the climatic and
vegetation changes in Malesia during the Cenozoic are two
important factors contributing to the present-day patterns of
moss distribution in Malesia.
Introduction
Since the distribution of many Malesian mosses
is intimately tied to the rain forest habitat, the
study of Malesian moss diversity and distribution
has become more urgent today because of the
increasing rate of destruction of rain forests
across the entire region. The complex patterns
of the distribution of mosses in the region is
matched by the diverse composition of the
Malesian moss taxa.
The impact and the biogeographical implication of the knowledge of moss distribution in
Malesia must not be underestimated. Based on
published information, the distribution of
Malesian mosses, like their seed plant counterparts, supports recognition of distinct eastern,
western and southern floristic provinces
(Steenis, 1950; Tan, 1984, 1992; Touw, 1992a,
1992b). The proposed scenario of a Central
Malesian province (see Johns, 1995) in place of
the South Malesian province is not well supBiogeography and Geological Evolution of SE Asia, pp. 235-241
Edited by Robert Hall and Jeremy D. Holloway
© 1998 Backhuys Publishers, Leiden, The Netherlands
ported by moss distribution patterns. On the
other hand, the distributions of moss taxa across
the Makassar Strait support the concept of a
Wallacean region over Wallace’s Line as a demarcation separating the Asiatic and Australasian floras. Nonetheless, the filtering effect of
this biogeographical barrier on the spore-producing mosses is not as dramatic as is the case
with seed plants (Tan, 1984, 1992; Hyvönen,
1989). Additionally, some areas in Borneo and
Palawan that harbour an aggregation of uncommon moss taxa sharing similar ecological preference and also the same pattern of distribution
have been taken to be refugia of species belonging to the Tertiary moist and the Quaternary dry
forests (Meijer, 1982; Tan, 1996).
An appreciation of the importance of
Malesian moss biogeography can be better
achieved with an overview of the composition
and affinities of Malesian mosses, which total
c.330 genera and 1,755 species. It is clear from
Table 1 that the majority of Malesian species of
mosses (c.60%) have evolved in situ during the
geological formation of the various island
groups, notably Borneo and New Guinea. Taxa
of clearly Laurasian and Gondwanan origins are
nearly equal in number. With the recent refinements in the plate tectonic history of the
Malesian region (see Hamilton, 1979; AudleyCharles, 1987; Hall, 1996), a review of the regional patterns of moss distribution, especially
those of the disjunctive taxa, is both instructive
and timely. Several of these patterns can now be
better explained by relating them to local plate
tectonic movements than by a long distance dis-
236
Table 1. Phytogeographical groupings/affinities of Malesian
mosses (330 genera and 1,755 species).
Cosmopolitan taxa
3.0%
N Hemisphere/Laurasia
4.0%
Pantropical
2.3%
Palaeotropical
1.0%
Palaeotropical and Oceania
4.8%
Tropical Asia (including Eastern Himalayas)
and Oceania
5.2%
Sri Lanka, S India, E Himalayas, Indochina, China,
Taiwan, Japan and Malesia
9.2%
Indochina, China, Taiwan, Japan and W Malesia
2.2%
Malesia
22.9%
Widespread
13.2%
W Malesia
6.4%
E Malesia
1.9%
S Malesia
1.4%
Narrow Endemics (restricted to 1-2 islands)
30.9%
W Malesia
11.3%
E Malesia
15.7%
S Malesia
3.9%
Malesia and Oceania
4.0%
S Hemisphere/Gondwana
4.5%
Disjunctive
3.0%
Not Certain
3.0%
persal hypothesis. This is especially true in the
bryogeographical interpretation of the floras between Luzon and Mindanao, and also between
the floras of North Borneo and Kalimantan Borneo. New geological evidence indicates an independent plate tectonic history for each of these
areas.
A word of caution is necessary here. In spite
of the large amount of new taxonomic information on Malesian mosses published in the
present decade, the moss flora of some pivotal
islands, such as Mindanao, Sulawesi and Halmahera, remains insufficiently known at present to
make definitive conclusions. It is probable that
some of the disjunction patterns outlined below
represent under-collection in intervening areas.
A good example to illustrate how improved taxonomy and new collections alter the distributional status of a species is found in Luisierella
barbula (Schwaegr.) Steere. This species was
long thought to be a neotropical taxon until two
collections from Java and New Caledonia, which
were erroneously named as Didymodon brevicaulis (Hampe ex C. Muell.) Fleisch., were correctly identified in 1977 (Touw, 1992a). To date,
the species is known additionally from Japan,
China, Borneo, Sulawesi, Java, the Lesser Sunda
Islands and New Caledonia. Its presence in Asia
is probably incompletely documented because
the species is a tiny moss of disturbed sites and
B. Tan
can be easily overlooked.
Another noteworthy revelation shown by the
distribution patterns of mosses is the relatively
slow rate of speciation in many groups. Studies
of fossilized mosses dated from Palaeozoic,
Mesozoic and the Tertiary, reveal a remarkable
similarity between the ancient and extant moss
floras supporting the alleged evolutionary conservatism of the plant group (Frahm, 1994).
Many of the fossil specimens can be identified to
families and genera that still exist today (Miller,
1984; Krassilov and Schuster, 1984; Ignatov,
1990). It is therefore not surprising that some
patterns of moss disjunction parallel those seen
in flowering plants and vertebrates at a higher
taxonomic level.
Noteworthy disjunctive patterns
Chameleion peguense (Besch.) Ellis & Eddy and
Horikawaea redfearnii B. C. Tan & P.-J. Lin
These two taxa (Fig.1) represent the continental
Asia and Philippine disjunction which was earlier called the Indochina-Philippines disjunction
by Tan (1984). Members of this group (c.2.2% of
the total Malesian species) are widespread in
continental Asia, becoming rare in wet parts of
archipelagic Malesia, and are often known only
from the Philippines (Luzon and Palawan, see
Fig.1). Some extend southward to the Malay peninsula, but they are absent from Borneo,
Sumatra and New Guinea. A broader version of
this pattern is seen in Pogonatum microstomum
(Dozy & Molk.) Dozy & Molk. (see Touw,
1992b, p.149, Fig.2), with additional populations
present also in Java and the Lesser Sunda Islands. Together, they probably represent denizens of monsoonal, semi-deciduous forest and
savannah communities that had a broad range
across tropical Asia during the Oligocene
(Morley, 1991) and Pleistocene (Morley and
Flenley, 1987; Heaney, 1991). The subsequent
climatic changes, beginning in the Miocene,
may have caused the fragmentation of the once
expansive, seasonally dry vegetation of SE Asia,
and its replacement by ever-wet rainforest such
as exists today in Borneo, Sumatra and New
Guinea. Consequently, mosses requiring seasonal
drought disappeared.
In the case of Horikawaea redfearnii, which
is known only from the seasonally dry forests of
Hainan and Palawan Islands (see Fig.1), the disjunctive pattern might have been brought about
by the drifting of the North Palawan-Mindoro
Disjunctive patterns of Malesian mosses
237
Fig.1. Distributions of Chaemeleion peguense (after Ellis, 1992) and Horikawaea redfearnii showing the continental AsiaPhilippines disjunction. Arrow indicates the possible direction of dispersal.
terrane from the vicinity of South China toward
its present position in the Philippines during the
Oligocene-Miocene (Hall, 1996). Additional examples of a similar disjunction across the South
China Sea are Sphagnum robinsonii Warnst.
(Indochina and northern Luzon) and S. luzonense
Warnst. (Indochina, Yunnan and Luzon).
A superficially similar pattern of disjunction,
but attributable to a different ecological factor, is
shown by Trachycladiella aurea (Mitt.) Menzel.
The species is a moss of humid montane forest;
its total range was mapped by Menzel and
Schultze-Motel (1994, p. 79, Fig.4). It is common
in the eastern Himalaya, scattered through the
mountains of S China, Taiwan, southern Japan
and northern Luzon, and reappears in the
mountains of Sulawesi, Seram and W Java. Its
present distribution appears to follow a hopping
migration along the Himalayan-Philippine
mountain track proposed by Steenis (1964). Its
presence on Mt. Kinabalu in Borneo and high
mountains in Mindanao can be predicted.
Dawsonia superba Grev., Bescherellia elegantissima Duby, Mittenia plumula (Mitt.) Lindb.,
Thuidium sparsum (Hook. f. & Wils.) Reichdt.
and Orthorrhynchium elegans (Hook. f. & Wils.)
Reichdt.
Bescherellia elegantissima Duby (Fig.3) and
Dawsonia superba Grev. are two mosses that
exhibit an Australasian/Oceania or South Malesia/Philippine disjunction. Members of this
group (about 4.5% of the total Malesian species)
are mostly widespread in rain forests in Australia, New Zealand and New Guinea, spreading
238
B. Tan
Fig.2. Distribution of Orthorrhynchium elegans showing a basically Gondwanan range. New Zealand populations are not
shown on the map. Locality information from S.-H. Lin (1984a, 1984b).
westward into Sulawesi or Halmahera, and
reaching northward to Mindanao Island in the
Philippines. They represent the Gondwana elements in the Malesian moss flora. On the basis
of Cenozoic plate tectonic history of SE Asia
(Hall, 1996), their arrival in Malesia probably followed the collision of SE Asia and the Australian
margin in the mid-Miocene.
A good example of this disjunction is seen in
Thuidium sparsum which is common in eastern
Australia, Tasmania and New Zealand, and reappears in S Malesia, touching the seasonally dry,
southeastern margin of Borneo and southern
Sulawesi (see Touw, 1992b, p.152, Fig. 5). Because of its absence in continental SE Asia,
Touw (1992b) attributed this peculiar pattern to
post-glacial colonization in Malesia after exten-
sive everwet rainforests had re-established in
Borneo and other wet parts of W Malesia. Another example of an Australasian moss that
probably became established post-glacially in W
Malesia is Mittenia plumula (Mitt.) Lindb. An
isolated population of this widespread luminescent moss occurring in Papua New Guinea, Australia, Tasmania and New Zealand, was recently
discovered on Mt. Kinabalu in North Borneo
(Tan, 1990).
In the case of Dawsonia superba, outlier
populations have penetrated the wet rain forest
in north Borneo. Since north Borneo has a different geological history from Kalimantan Borneo (Michaux, 1991; Hall, 1996), the north
Bornean populations of D. superba most likely
originated from Mindanao and reached Sabah,
Disjunctive patterns of Malesian mosses
Brunei and Sarawak via either the Palawan or
Sulu archipelagic corridor.
As to the Philippine island groups, new geological evidence has shown the island of
Mindanao to have an origin south of the equator
(Hall, 1996). The movement of Mindanao since
the mid-Eocene from 140oE, 10oS to its present
position in the Philippines could have provided
an opportunity for exchange of plant taxa between the W and E Malesia provinces before the
arrival of the New Guinean block. Compared to
Luzon Island, Mindanao has a moss flora with an
apparent Australasian influence. Good examples
of disjunction between Mindanao (absent from
Luzon and the Visayas Islands) and E Malesia
(mainly New Guinea) are Ectropotheciopsis novoguineensis (Geh.) Fleisch. and Plagiotheciopsis
oblonga (Broth.) Broth. (Tan, 1984).
Among the many Malesian Gondwanan taxa,
Orthorrhynchium elegans has a broad, discontinuous range reaching the Lesser Sunda Islands
and Mindanao (Fig.2). West of the Wallace Line,
this species is known additionally from Sri
Lanka, S India and northern Sumatra, but is absent from Borneo and the Malay peninsula. The
species probably reached Malesia by two separate events of introduction: the arrival of the
Shan-Thai-Sumatra terranes in SE Asia in late
Cretaceous or early Paleocene (Michaux, 1991)
and the joining of the Australia-New Guinean
plate in the late Miocene (Burrett et al., 1991).
Aongstroemia orientalis Mitt., Tortula caroliniana
Andrews and Diphyscium chiapense Norris
These are three species representing East Asia
and Tropical American disjunction. They can
also be considered examples of the amphi-Pacific disjunction. They constitute about 1% of the
Malesian mosses (see Table 1). Tortula caroliniana is common in the SE United States, and
Central and South Americas, with a disjunct
population in Papua New Guinea. In contrast,
Aongstroemia orientalis is widespread in the
mountains in Asia, being reported from the E
Himalaya, India, Indochina, China, Japan, Philippines (northern Luzon), Borneo (Mt.
Kinabalu), Java (G. Sumbing), Lombok (G.
Rinjani), and is found disjunctively in high
mountains of Mexico and Guatemala. Their absence in tropical Africa seems to preclude a
common Tethyan origin. The unique pattern of
distribution of Diphyscium chiapense needs special mention. The species is known from Japan
where it is locally widespread from Honshu to
239
Shikoku, Mindanao (Mt. Kitanglad) and Mexico
(Chiapas). It possibly represents an example of
long distance and chance dispersal, although
the ecology of this mainly terrestrial moss, as
well as its sessile capsules and seemingly large
and green spores, would argue against a long
distance dispersability.
Entodon concinnus (De Not.) Par., Rhytidium
rugosum (Hedw.) Kindb. and Hageniella micans
(Mitt.) B. C. Tan and Y. Jia
These three species have a wide, albeit discontinuous, circum-boreal range, with scattered
outlier populations in tropical Asia/Malesia and/
or tropical America. Outside the northern hemisphere, Entodon concinnus is known from
Papua New Guinea (Mt. Sarawaket, Mt. Wilhelm
and Huon peninsula) and Ecuador (Enroth,
1991a). Interestingly, the circum-boreal and
calcicole Rhytidium rugosum also has a single
Malesian station in Irian Jaya of New Guinea
(Schultze-Motel, 1963). In Hageniella micans
(Mitt.) Tan & Jia, a recent revision (unpublished
data, 1997) demonstrates a broad and discontinuous range which includes Britain, W Europe,
SW China, Taiwan, Philippines (Luzon), Borneo
(Mt. Kinabalu), Java (Mt. Gedeh), Hawaii,
Canada (British Columbia), E United States and
Mexico (Oaxaca). On a smaller scale, Brachymenium bryoides Hook. ex Schwaegr. has a
range from the Himalayas to S India and is
disjunctly present in Papua New Guinea. This
type of disjunctive pattern is best explained by
long distance and chance dispersal. In the case
of Rhytidium rugosum and Hageniella micans,
populations with sporophytes are infrequent
throughout their ranges, therefore, long distance
dispersibility must be inefficient and chancy.
Brachymenium capitulatum (Mitt.) Par. and
Caduciella mariei (Besch.) Enroth
Brachymenium capitulatum has a reported
range of continental Africa, Madagascar, Taiwan
and Papua New Guinea. It exhibits a tropical
Asian and tropical African disjunction which has
been summarized and discussed by Pócs (1992)
who provided additional examples of liverworts
showing the same disjunction pattern. Caduciella mariei, which has been reported from Tanzania, the Comoro Islands, India (Assam), SW
China, Indochina, Malesia, Oceania and Australia (Queensland), is another example (Fig.3).
Many members of this group, though, are not
240
B. Tan
0
Fig.3. Distributions of Diphyscium chiapense, Caduciella mariei and Bescherellia elegantissima. Distribution of Diphyscium
chiapense shows an E Asiatic and Tropical American or amphi-Pacific disjunction. Locality information from Deguchi (1997).
Distribution of Caduciella mariei shows a Tropical Africa and Tropical Asia disjunction. Locality information from Pócs (1992)
and Enroth (1991a, b). Distribution of Bescherellia elegantissima includes eastern Australia and Papua New Guinea, with outlier
populations in Mindanao, Buru, New Caledonia and Fiji. Locality information from Sastre-Ines (1987).
known from the African continent, but only
from Madagascar, in addition to SE Asia. Others
have a more or less continuous range across the
Old World tropics and can be considered
palaeo-tropical taxa. According to Pócs (1992),
they represent either the fragmented parts of a
former continuous Gondwana range or the result of chance dispersal between extant
populations on the two continents.
Takakia lepidozioides Hatt. & Inoue
This is probably the most widely disjunctive
moss species in the world. Individual
populations have been collected from small areas in coastal British Columbia and Alexander
archipelago of Alaska, the Japanese Alps in
Honshu, E Nepal, SE Tibet of China, and Mt.
Kinabalu in north Borneo. The widely separated
populations in Asia and North America and the
restrictive habitat of this species seem to imply a
long history of survival probably dating back to
the time of the Pangaea supercontinent, with
subsequent extinction of intervening populations. However, Schuster (1976) considered the
distribution of T. lepidozioides to have resulted
from the northward drifting of the Indian plate,
followed by dispersal events across the land to
reach North America.
Syrrhopodon strictus Thwaites & Mitt. and
Fissidens subbryoides Hampe ex Gang
These are species of Malesian mosses with an
odd or seemingly erratic disjunctive distribution.
For example, Syrrhopodon strictus is known only
from Sri Lanka and Irian Jaya of Indonesia,
whereas Fissidens subbryoides has a few sporadic reports from E Nepal, Assam (India), the
Andaman Islands and Seram (Indonesia). Apparently, they represent species of insufficiently
known distribution awaiting more collections
from the vast intervening and neighbouring regions. They could also be artefacts of inaccurate
taxonomy.
Conclusions
As our knowledge of plate tectonic history of
the Malesian region progresses, there is a corresponding need to learn more about the detailed
Disjunctive patterns of Malesian mosses
distribution of various plant species, including
mosses, across this vast region, as well as their
ecology, reproductive and dispersal biology. Information from these sources can elucidate and
corroborate hypotheses that lead us to a deeper
understanding of the co-evolution of the geological environs and the flora it has come to support.
Acknowledgements
I am grateful to Prof. R. Hall and colleagues at
the Natural History Museum for making it possible for me to attend the symposium. Drs. W. B.
Schofield and D. Boufford kindly read and criticized the draft of this paper. The comments of
the two reviewers and the editor of this volume
are equally appreciated. Travel support to attend the symposium was provided by HUH
through the Director M. Donoghue’s Office and
is acknowledged.
References
Audley-Charles, M. G. 1987. Dispersal of Gondwanaland:
relevance to evolution of the angiosperms. In Biogeographical Evolution of the Malay Archipelago. pp.5-25.
Edited by T. C. Whitmore, Clarendon Press, Oxford.
Burrett, C., Duhig, N., Berry R. and Varne, R. 1991. Asian
and southwestern Pacific continental terranes derived
from Gondwana, and their biogeographic significance.
Australian Systematic Botany 4: 13-24.
Deguchi, H., Ueno, J. and Yamaguchi, R. 1997. Taxonomic
notes on Diphyscium species with unipapillose leaf cells.
Journal of Hattori Botanical Laboratory 82: 99-104.
Ellis, L. 1992. Towards a moss flora of southern India.
Bryobrothera 1: 133-136.
Enroth, J. 1991a. Bryophyte flora of the Huon peninsula,
Papua New Guinea. XLII. Entodontaceae (Musci). Acta
Botanica Fennica 143: 43-55.
Enroth, J. 1991b. Notes on the Neckeraceae (Musci). 10. The
taxonomic relationships of Pinnatella mariei, with the
description of Caduciella (Leptodontaceae). Journal of
Bryology 16: 611-618.
Frahm, J.-P. 1994. Moose-lebende Fossilien. Biologie in
unseren Zeit 24: 120-124.
Hall, R. 1996. Reconstructing Cenozoic SE Asia. In Tectonic
Evolution of Southeast Asia. Edited by R. Hall & D. J.
Blundell, Geological Society Special Publication 106:
153-184.
Hamilton, W. 1979. Tectonics of the Indonesian region.
United States Geological Survey Professional Paper 1078:
345pp.
Heaney, L. R. 1991. A synopsis of climatic and vegetational
changes in Southeast Asia. Climatic Change 19: 53-61.
Hyvönen, J. 1989. On the bryogeography of Western Melanesia. Journal of Hattori Botanical Laboratory 66: 231-254.
Ignatov, M. S. 1990. Upper Permian mosses from the Russian platform. Paleontographica 217: 147-189.
241
Johns, R. J. 1995. Malesia – an introduction. Curtis’s
Botanical Magazine 12: 52-62.
Krassilov, V. A. and R. M. Schuster. 1984. Paleozoic and
Mesozoic fossils. In New Manual of Bryology, v.2. Edited
by R. M. Schuster, Hattori Botanical Laboratory, Nichinan.
Lin, S.-H. 1984a. A taxonomic revision of Phyllogoniaceae
(Bryopsida). Part II. Journal of Taiwan Museum 37: 1-54.
Lin, S.-H. 1984b. Contribution to the knowledge of
Orthorrhynchiaceae (2) Orthorrhynchium specimens in
the Rijksherbarium, Leiden, The Netherlands. Yushania
1(2): 31-44.
Meijer, W. 1982. Plant refuges in the Indo-Malesian region,
pp. 576-584. In Biological Diversification in the Tropics.
Edited by G. T. Prance, Columbia University Press, New
York.
Menzel, M. and Schultze-Motel, W. 1994. Taxonomische
notizen zur Gattung Trachycladiella (Fleisch.), stat. nov.
(Meteoriaceae, Leucodontales). Journal of Hattori Botanical Laboratory 75: 73-83.
Michaux, B. 1991. Distributional patterns and tectonic development in Indonesia: Wallace reinterpreted. Australian Systematic Botany 4: 25-36.
Miller, N. G. 1984. Tertiary and Quaternary fossils, pp. 11941232. In New Manual of Bryology, vol. 2. Edited by R. M.
Schuster, Hattori Botanical Laboratory, Nichinan.
Morley, R. 1991. Tertiary stratigraphic palynology in Southeast Asia: current status and new directions. Bulletin of
Geological Society of Malaysia 28: 1-36.
Morley, R. and Flenley, J. R. 1987. Late Cainozoic vegetational and environmental changes in the Malay Archipelago, pp. 50-59. In Biogeographical Evolution of the
Malay Archipelago. Edited by T. C. Whitmore, Clarendon
Press, Oxford.
Pócs, T. 1992. Correlation between the tropical African and
Asian bryofloras II. Bryobrothera 1: 35-47.
Sastre-De Jesus, I. 1987. Revision of the Cyrtopodaceae and
transfer of Cyrtopodendron to the Pterobryaceae. Memoirs of the New York Botanical Gardens 45: 709-721.
Schultze-Motel, W. 1963. Vorläufiges Verzeichnis der
Laubmoose von Neuguinea. Willdenovia 3: 399-549.
Schuster, R. M. 1976. Plate tectonics and its bearing on the
geographical origin and dispersal of angiosperms, pp.
48-138. In Origin and Early Evolution of Angiosperms.
Edited by C. B. Beck, Columbia University Press, New
York.
Steenis, C. G. G. J. van. 1950. The delimitation of Malaysia
and its main plant geographic regions. Flora Malesiana
Series 1, 1: lxxvi-cvi.
Steenis, C. G. G. J. van. 1964. Plant geography of the mountain flora of Mt. Kinabalu. Proceedings of Royal Society
of London, Series B, Biological Sciences 161: 7-38.
Tan, B. C. 1984. A reconsideration of the affinity of Philippine moss flora. Journal of Hattori Botanical Laboratory
55: 13-22.
Tan, B. C. 1990. Six new taxa of Malesian mosses. Bryologist
93: 429-437.
Tan, B. C. 1992. Philippine Muscology (1979-1989).
Bryobrothera 1: 137-141.
Tan, B. C. 1996. Biogeography of Palawan mosses. Australian Systematic Botany 9: 193-203.
Touw, A. 1992a. A survey of the mosses of the Lesser Sunda
Islands (Nusa Tenggara), Indonesia. Journal of the
Hattori Botanical Laboratory 71: 289-366.
Touw, A. 1992b. Biogeographical notes on the Musci of
South Malesia, and of the Lesser Sunda Islands in particular. Bryobrothera 1: 143-155.
242
B. Tan