Noteworthy Disjunctive Patterns of Malesian Mosses

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 ported by moss distribution patterns On the other hand, the distributions of moss taxa across A review of some noteworthy patterns of disjunction of the Makassar Strait support the concept of a Malesian moss distributions is presented Correlation with Wallacean region over Wallaces Line as a de- new information from the plate tectonic history of the marcation separating the Asiatic and Australa- Malesian region offers a new interpretation of the origin and sian floras Nonetheless, the filtering effect of migration of Malesian mosses Although long distance and chance dispersal remain important explanations for local this biogeographical barrier on the spore-pro- plant distribution patterns, it appears that the climatic and ducing mosses is not as dramatic as is the case vegetation changes in Malesia during the Cenozoic are two with seed plants (Tan, 1984, 1992; Hyvönen, important factors contributing to the present-day patterns of 1989) Additionally, some areas in Borneo and moss distribution in Malesia Palawan that harbour an aggregation of uncom- mon moss taxa sharing similar ecological prefer- ence and also the same pattern of distribution Introduction have been taken to be refugia of species belong- ing to the Tertiary moist and the Quaternary dry Since the distribution of many Malesian mosses forests (Meijer, 1982; Tan, 1996) is intimately tied to the rain forest habitat, the An appreciation of the importance of study of Malesian moss diversity and distribution Malesian moss biogeography can be better has become more urgent today because of the achieved with an overview of the composition increasing rate of destruction of rain forests and affinities of Malesian mosses, which total across the entire region The complex patterns c 330 genera and 1,755 species It is clear from of the distribution of mosses in the region is Table 1 that the majority of Malesian species of matched by the diverse composition of the mosses (c%60%) have evolved in situ during the Malesian moss taxa geological formation of the various island The impact and the biogeographical implica- groups, notably Borneo and New Guinea Taxa tion of the knowledge of moss distribution in of clearly Laurasian and Gondwanan origins are Malesia must not be underestimated Based on nearly equal in number With the recent refine- published information, the distribution of ments in the plate tectonic history of the Malesian mosses, like their seed plant counter- Malesian region (see Hamilton, 1979; Audley- parts, supports recognition of distinct eastern, Charles, 1987; Hall, 1996), a review of the re- western and southern floristic provinces gional patterns of moss distribution, especially (Steenis, 1950; Tan, 1984, 1992; Touw, 1992a, those of the disjunctive taxa, is both instructive 1992b) The proposed scenario of a Central and timely Several of these patterns can now be Malesian province (see Johns, 1995) in place of better explained by relating them to local plate the South Malesian province is not well sup- tectonic movements than by a long distance dis-

Table 1 Phytogeographical groupings/affinities of Malesian can be easily overlooked mosses (330 genera and 1,755 species) Another noteworthy revelation shown by the distribution patterns of mosses is the relatively Cosmopolitan taxa 30% slow rate of speciation in many groups Studies N Hemisphere/Laurasia 40% of fossilized mosses dated from Palaeozoic, Pantropical 23% Mesozoic and the Tertiary, reveal a remarkable Palaeotropical 10% similarity between the ancient and extant moss Palaeotropical and Oceania 48% Tropical Asia (including Eastern Himalayas) floras supporting the alleged evolutionary con- and Oceania 52% servatism of the plant group (Frahm, 1994) Sri Lanka, S India, E Himalayas, Indochina, China, Many of the fossil specimens can be identified to Taiwan, Japan and Malesia 92% families and genera that still exist today (Miller, Indochina, China, Taiwan, Japan and W Malesia 22% 1984; Krassilov and Schuster, 1984; Ignatov, Malesia 229% Widespread 132% 1990) It is therefore not surprising that some W Malesia 64% patterns of moss disjunction parallel those seen E Malesia 19% in flowering plants and vertebrates at a higher S Malesia 14% taxonomic level Narrow Endemics (restricted to 1-2 islands) 309% W Malesia 113% E Malesia 157% S Malesia 39% Noteworthy disjunctive patterns Malesia and Oceania 40% S Hemisphere/Gondwana 45% Chameleion peguense (Besch ) Ellis & Eddy and Disjunctive 30% Horikawaea redfearnii B C Tan & P -J Lin Not Certain 30% These two taxa (Fig 1) represent the continental Asia and Philippine disjunction which was ear- lier called the Indochina-Philippines disjunction persal hypothesis This is especially true in the by Tan (1984) Members of this group (c 2 2% of bryogeographical interpretation of the floras be- the total Malesian species) are widespread in tween Luzon and Mindanao, and also between continental Asia, becoming rare in wet parts of the floras of North Borneo and Kalimantan Bor- archipelagic Malesia, and are often known only neo New geological evidence indicates an inde- from the Philippines (Luzon and Palawan, see pendent plate tectonic history for each of these Fig 1) Some extend southward to the Malay pe- areas ninsula, but they are absent from Borneo, A word of caution is necessary here In spite Sumatra and New Guinea A broader version of of the large amount of new taxonomic informa- this pattern is seen in Pogonatum microstomum tion on Malesian mosses published in the (Dozy & Molk ) Dozy & Molk (see Touw, present decade, the moss flora of some pivotal 1992b, p 149, Fig 2), with additional populations islands, such as Mindanao, Sulawesi and Halma- present also in Java and the Lesser Sunda Is- hera, remains insufficiently known at present to lands Together, they probably represent deni- make definitive conclusions It is probable that zens of monsoonal, semi-deciduous forest and some of the disjunction patterns outlined below savannah communities that had a broad range represent under-collection in intervening areas across tropical Asia during the Oligocene A good example to illustrate how improved tax- (Morley, 1991) and Pleistocene (Morley and onomy and new collections alter the distribu- Flenley, 1987; Heaney, 1991) The subsequent tional status of a species is found in Luisierella climatic changes, beginning in the Miocene, barbula (Schwaegr ) Steere This species was may have caused the fragmentation of the once long thought to be a neotropical taxon until two expansive, seasonally dry vegetation of SE Asia, collections from Java and New Caledonia, which and its replacement by ever-wet rainforest such were erroneously named as Didymodon brevi- as exists today in Borneo, Sumatra and New caulis (Hampe ex C Muell ) Fleisch , were cor- Guinea Consequently, mosses requiring seasonal rectly identified in 1977 (Touw, 1992a) To date, drought disappeared the species is known additionally from Japan, In the case of Horikawaea redfearnii, which China, Borneo, Sulawesi, Java, the Lesser Sunda is known only from the seasonally dry forests of Islands and New Caledonia Its presence in Asia Hainan and Palawan Islands (see Fig 1), the dis- is probably incompletely documented because junctive pattern might have been brought about the species is a tiny moss of disturbed sites and by the drifting of the North Palawan-Mindoro Disjunctive patterns of Malesian mosses 237

Fig1 Distributions of Chaemeleion peguense (after Ellis, 1992) and Horikawaea redfearnii showing the continental Asia- Philippines disjunction Arrow indicates the possible direction of dispersal terrane from the vicinity of South China toward migration along the Himalayan-Philippine its present position in the Philippines during the mountain track proposed by Steenis (1964) Its Oligocene-Miocene (Hall, 1996) Additional ex- presence on Mt Kinabalu in Borneo and high amples of a similar disjunction across the South mountains in Mindanao can be predicted China Sea are Sphagnum robinsonii Warnst (Indochina and northern Luzon) and S% luzonense Dawsonia superba Grev , Bescherellia elegant- Warnst (Indochina, Yunnan and Luzon) issima Duby, Mittenia plumula (Mitt ) Lindb , A superficially similar pattern of disjunction, Thuidium sparsum (Hook f & Wils ) Reichdt but attributable to a different ecological factor, is and Orthorrhynchium elegans (Hook f & Wils ) shown by Trachycladiella aurea (Mitt ) Menzel Reichdt The species is a moss of humid montane forest; its total range was mapped by Menzel and Bescherellia elegantissima Duby (Fig 3) and Schultze-Motel (1994, p 79, Fig 4) It is common Dawsonia superba Grev are two mosses that in the eastern Himalaya, scattered through the exhibit an Australasian/Oceania or South Mal- mountains of S China, Taiwan, southern Japan esia/Philippine disjunction Members of this and northern Luzon, and reappears in the group (about 4 5% of the total Malesian species) mountains of Sulawesi, Seram and W Java Its are mostly widespread in rain forests in Aus- present distribution appears to follow a hopping tralia, New Zealand and New Guinea, spreading 238 B% Tan

Fig2 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 sive everwet rainforests had re-established in reaching northward to Mindanao Island in the Borneo and other wet parts of W Malesia An- Philippines They represent the Gondwana ele- other example of an Australasian moss that ments in the Malesian moss flora On the basis probably became established post-glacially in W of Cenozoic plate tectonic history of SE Asia Malesia is Mittenia plumula (Mitt ) Lindb An (Hall, 1996), their arrival in Malesia probably fol- isolated population of this widespread lumines- lowed the collision of SE Asia and the Australian cent moss occurring in Papua New Guinea, Aus- margin in the mid-Miocene tralia, Tasmania and New Zealand, was recently A good example of this disjunction is seen in discovered on Mt Kinabalu in North Borneo Thuidium sparsum which is common in eastern (Tan, 1990) Australia, Tasmania and New Zealand, and reap- In the case of Dawsonia superba, outlier pears in S Malesia, touching the seasonally dry, populations have penetrated the wet rain forest southeastern margin of Borneo and southern in north Borneo Since north Borneo has a dif- Sulawesi (see Touw, 1992b, p 152, Fig 5) Be- ferent geological history from Kalimantan Bor- cause of its absence in continental SE Asia, neo (Michaux, 1991; Hall, 1996), the north Touw (1992b) attributed this peculiar pattern to Bornean populations of D% superba most likely post-glacial colonization in Malesia after exten- originated from Mindanao and reached Sabah, Disjunctive patterns of Malesian mosses 239

Brunei and Sarawak via either the Palawan or Shikoku, Mindanao (Mt Kitanglad) and Mexico Sulu archipelagic corridor (Chiapas) It possibly represents an example of As to the Philippine island groups, new geo- long distance and chance dispersal, although logical evidence has shown the island of the ecology of this mainly terrestrial moss, as Mindanao to have an origin south of the equator well as its sessile capsules and seemingly large (Hall, 1996) The movement of Mindanao since and green spores, would argue against a long the mid-Eocene from 140oE, 10oS to its present distance dispersability position in the Philippines could have provided an opportunity for exchange of plant taxa between the W and E Malesia provinces before the Entodon concinnus (De Not ) Par , Rhytidium arrival of the New Guinean block Compared to rugosum (Hedw ) Kindb and Hageniella micans Luzon Island, Mindanao has a moss flora with an (Mitt ) B C Tan and Y Jia apparent Australasian influence Good examples of disjunction between Mindanao (absent from These three species have a wide, albeit discon- Luzon and the Visayas Islands) and E Malesia tinuous, circum-boreal range, with scattered (mainly New Guinea) are Ectropotheciopsis novo- outlier populations in tropical Asia/Malesia and/ guineensis (Geh ) Fleisch and Plagiotheciopsis or tropical America Outside the northern hemi- oblonga (Broth ) Broth (Tan, 1984) sphere, Entodon concinnus is known from Among the many Malesian Gondwanan taxa, Papua New Guinea (Mt Sarawaket, Mt Wilhelm Orthorrhynchium elegans has a broad, discon- and Huon peninsula) and Ecuador (Enroth, tinuous range reaching the Lesser Sunda Islands 1991a) Interestingly, the circum-boreal and and Mindanao (Fig 2) West of the Wallace Line, calcicole Rhytidium rugosum also has a single this species is known additionally from Sri Malesian station in Irian Jaya of New Guinea Lanka, S India and northern Sumatra, but is ab- (Schultze-Motel, 1963) In Hageniella micans sent from Borneo and the Malay peninsula The (Mitt ) Tan & Jia, a recent revision (unpublished species probably reached Malesia by two sepa- data, 1997) demonstrates a broad and discon- rate events of introduction: the arrival of the tinuous range which includes Britain, W Europe, Shan-Thai-Sumatra terranes in SE Asia in late SW China, Taiwan, Philippines (Luzon), Borneo Cretaceous or early Paleocene (Michaux, 1991) (Mt Kinabalu), Java (Mt Gedeh), Hawaii, and the joining of the Australia-New Guinean Canada (British Columbia), E United States and plate in the late Miocene (Burrett et al , 1991) Mexico (Oaxaca) On a smaller scale, Brachy- menium bryoides Hook ex Schwaegr has a range from the Himalayas to S India and is Aongstroemia orientalis Mitt , Tortula caroliniana disjunctly present in Papua New Guinea This Andrews and Diphyscium chiapense Norris type of disjunctive pattern is best explained by long distance and chance dispersal In the case These are three species representing East Asia of Rhytidium rugosum and Hageniella micans, and Tropical American disjunction They can populations with sporophytes are infrequent also be considered examples of the amphi-Pa- throughout their ranges, therefore, long distance cific disjunction They constitute about 1% of the dispersibility must be inefficient and chancy Malesian mosses (see Table 1) Tortula caroliniana is common in the SE United States, and Brachymenium capitulatum (Mitt ) Par and Central and South Americas, with a disjunct Caduciella mariei (Besch ) Enroth population in Papua New Guinea In contrast, Aongstroemia orientalis is widespread in the Brachymenium capitulatum has a reported mountains in Asia, being reported from the E range of continental Africa, Madagascar, Taiwan Himalaya, India, Indochina, China, Japan, Phil- and Papua New Guinea It exhibits a tropical ippines (northern Luzon), Borneo (Mt Asian and tropical African disjunction which has Kinabalu), Java (G Sumbing), Lombok (G been summarized and discussed by Pócs (1992) Rinjani), and is found disjunctively in high who provided additional examples of liverworts mountains of Mexico and Guatemala Their ab- showing the same disjunction pattern Caduci- sence in tropical Africa seems to preclude a ella mariei, which has been reported from Tan- common Tethyan origin The unique pattern of zania, the Comoro Islands, India (Assam), SW distribution of Diphyscium chiapense needs spe- China, Indochina, Malesia, Oceania and Aus- cial mention The species is known from Japan tralia (Queensland), is another example (Fig 3) where it is locally widespread from Honshu to Many members of this group, though, are not 240 B% Tan

Fig3 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 the northward drifting of the Indian plate, from Madagascar, in addition to SE Asia Others followed by dispersal events across the land to have a more or less continuous range across the reach North America Old World tropics and can be considered palaeo-tropical taxa According to Pócs (1992), Syrrhopodon strictus Thwaites & Mitt and they represent either the fragmented parts of a Fissidens subbryoides Hampe ex Gang former continuous Gondwana range or the re- sult of chance dispersal between extant These are species of Malesian mosses with an populations on the two continents odd or seemingly erratic disjunctive distribution For example, Syrrhopodon strictus is known only Takakia lepidozioides Hatt & Inoue from Sri Lanka and Irian Jaya of Indonesia, whereas Fissidens subbryoides has a few spo- This is probably the most widely disjunctive radic reports from E Nepal, Assam (India), the moss species in the world Individual Andaman Islands and Seram (Indonesia) Appar- populations have been collected from small ar- ently, they represent species of insufficiently eas in coastal British Columbia and Alexander known distribution awaiting more collections archipelago of Alaska, the Japanese Alps in from the vast intervening and neighbouring re- Honshu, E Nepal, SE Tibet of China, and Mt gions They could also be artefacts of inaccurate Kinabalu in north Borneo The widely separated taxonomy 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 Conclusions the time of the Pangaea supercontinent, with subsequent extinction of intervening popula- As our knowledge of plate tectonic history of tions However, Schuster (1976) considered the the Malesian region progresses, there is a corre- distribution of T% lepidozioides to have resulted sponding need to learn more about the detailed Disjunctive patterns of Malesian mosses 241 distribution of various plant species, including Johns, R J 1995 Malesia an introduction Curtiss mosses, across this vast region, as well as their Botanical Magazine 12: 52-62 Krassilov, V A and R M Schuster 1984 Paleozoic and ecology, reproductive and dispersal biology In- Mesozoic fossils In New Manual of Bryology, v2 Edited formation from these sources can elucidate and by R M Schuster, Hattori Botanical Laboratory, Nichinan corroborate hypotheses that lead us to a deeper Lin, S-H 1984a A taxonomic revision of Phyllogoniaceae understanding of the co-evolution of the geo- (Bryopsida) Part II Journal of Taiwan Museum 37: 1-54 logical environs and the flora it has come to sup- Lin, S-H 1984b Contribution to the knowledge of Orthorrhynchiaceae (2) Orthorrhynchium specimens in port the Rijksherbarium, Leiden, The Netherlands Yushania 1(2): 31-44 Meijer, W 1982 Plant refuges in the Indo-Malesian region, Acknowledgements pp 576-584 In Biological Diversification in the Tropics Edited by G T Prance, Columbia University Press, New York I am grateful to Prof R Hall and colleagues at Menzel, M and Schultze-Motel, W 1994 Taxonomische the Natural History Museum for making it possi- notizen zur Gattung Trachycladiella (Fleisch), stat nov ble for me to attend the symposium Drs W B (Meteoriaceae, Leucodontales) Journal of Hattori Bo- Schofield and D Boufford kindly read and criti- tanical Laboratory 75: 73-83 cized the draft of this paper The comments of Michaux, B 1991 Distributional patterns and tectonic de- velopment in Indonesia: Wallace reinterpreted Austral- the two reviewers and the editor of this volume ian Systematic Botany 4: 25-36 are equally appreciated Travel support to at- Miller, N G 1984 Tertiary and Quaternary fossils, pp 1194- tend the symposium was provided by HUH 1232 In New Manual of Bryology, vol 2 Edited by R M through the Director M Donoghues Office and Schuster, Hattori Botanical Laboratory, Nichinan is acknowledged Morley, R 1991 Tertiary stratigraphic palynology 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