Tropical Bryology, Volume 2 (1990)
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As currently understood, the Lejeuneaceae flora of Australia consists of 122 species in 27 genera. The family occurs almost exclusively in rainforested areas along the eastern coast of the continent. Based on species composition, three floristic regions are recognized: tropical, subtropical and temperate. The tropical region contains 80 percent of the total number of Lejeuneaceae found in Australia, the subtropical region contains 45 percent, and the temperate region only 15 percent of the total flora. The affinities of the Lejeuneaceae in the tropical and subtropical regions are strongest with the Asian flora, and those of the temperate region are strongest with the New Zealand flora. The diversity of the Lejeuneaceae flora in Australia is higher than might be expected for a non-equatorial region. This diversity may result from the wide variety of rainforest habitats that are available along both latitudinal and altitudinal gradients. The temperate flora is probably derived from that which existed in Australia, New Zealand, Antarctica and probably southern South America prior to the breakup of Gondwanaland. The modern tropical flora is probably a mixture of species that were part of the original northern Gondwanan flora and those that have invaded more recently.
The generic and specific affinities of the Philippine, Bornean and New Guinean hepatic floras were analyzed by calculating the Kroeber's percentage of similarity on the basis of recently published checklists. It is observed that the overall affinities parallel that exhibited by local moss floras except for one important difference. For the three areas, the number and distribution of species of large, actively evolving hepatic genera are noted to be disparate and with few shared taxa. Contrastingly, the large and actively evolving moss genera produce consistently large number of species in all three areas with an equally large number of shared taxa. The strong dependence of many hepatic taxa on asexual reproduction and the poor spore dispersability are accepted as the best explanation to this phenomenon.
The neotropical hepatic flora, predominantly constituted by members of the Jungermanniales and Metzgeriales, includes a disproportionate number of genera which are endemic (over 38) and a number which evidently originated here but have shown slight and in a geological sense, modern dispersal by solitary species. Endemism is confined almost to the Jungermanniales; it is to a large degree of a unique sort: confined to highly apomorphic derivatives, often extremely reduced, sometimes confervoid or thalloid (aside from 'normal' sexual branches). These endemics are derivatives of basically cool-Gondwanalandic suborders, chiefly Lepidoziineae and Cephaloziineae which, in the Antipodes today include a wide range of plesiomorphic taxa. The highest proportion of endemic genera, often stenotypic (1-3 species each) occurs in the upper montane zone: from upper Andean forest to páramo, to the edge of permanent snow and ice; a smaller number occurs at upper elevations of the Guyana Shield, but more occur in the riverine systems that dissect this shield. The taxa found there (i.a., Zoopsidella, Pteropsiella, Schusterolejeunea, Cephalantholejeunea) are among the most apomorphic of all hepatics. The amount of endemism is shown to be higher than in any comparable region of the globe. It is assumed that this is owing to: (a) isolation, exceeding 40 m.y. and probably exceeding 60 m.y.; (b) continuous tectonic activity, preserving the 'raw' and 'pioneer' habitats which are necessary for the survival of 'fugitive', 'shuttle' and other types of pioneer taxa; (c) the antiquity of the Guyana Shield and its riverine system; (d) creation of striking ecological gradients, many biotic islands; (e) fluctuation in extent and degree of isolation of these 'islands', leading to (f) rapid evolution due to genetic drift and perhaps enhanced selection pressures. It is concluded that part of the complexity of the flora is due to preservation of some elements on the old Guyana Shield but most is due to relatively rapid evolution during Tertiary times. A final contributing element has been the fact that movement of the South American plate has been primarily from east to west, so that the relevant land area has not been rafted into regions with very different climatic parameters: the degree of extinction seen in, e.g., India and Australia is not evident here. It is concluded that the amount of endemism seen, and its extreme kinds, 'need' in excess of the 40-60 m.y. time span which seems available. In particular, the large number of high elevation endemics, some (such as Ruizanthus) very isolated, cannot be satisfactorily explained by assuming their evolution in the few million years available since alpine regions were created by the rise of the Andes. It is almost necessary to conclude that limited 'pre-Andes' must have existed and that the ancestors of the isolated taxa seen today in alpine loci in Colombia and Venezuela originated elsewhere. The other side of the outlined scenario is that with the near-total isolation of tropical America until the Andes were elevated, and until the Pliocene connection to North America arose, one would expect to see few and scattered intruders from cool-Gondwanalandic areas and from Laurasia. The modern flora reflects exactly this.
Recent conclusions on the limits of the Leucobryaceae and on the function of the Leucobryaceous leaf are used as basis for further observations on evolution of the group. Eight genera are recognized in the family; 1. Leucobryum, 2. Steyermarkiella, 3. Ochrobryum, 4. Arthrocormus, 5. Schistomitrium, 6. Holomitriopsis, 7. Cladopodanthus, and 8. Octoblepharum. The leaf form, capsule shape, and peristome substructure of Leucobryum seems to derive from a Campylopus-type member of the Dicranaceae. Four basic stages are noted in the functional evolution of the family. 1. The stratification of the leaf into leucocysts and chlorocyst layers with leucocysts holding water and internally generated gas; 2. The shift from soil substrates seen mostly in Temperate Zone Leucobryum to rotten wood substrates or epiphytism; 3. Increasing reliance on vegetative reproduction with reduction of reliance on sporophytes; 4. Morphogenetic increase of the number of chlorocysts in the leaf. Geographical concentrations of the genera are noted, and distributions between hemispheres are apparently mostly by way of the South Atlantic. The use of functional considerations in evolutionary studies is emphasized. The retention of paraphyletic groups in taxonomy is defended.
In many ways, it is presumptuous for me to speak on the mosses of the tropical regions of China. Many consider the knowledge about the taxonomy, ecology, and geography of tropical bryophytes inadequate (Pócs 1982; Schuster 1983; Richards 1984), and this is certainly the case for the bryophytes of the tropical regions of China. The taxonomy of Chinese taxa is generally in a state of disarray. Early workers, both Chinese and others, have tended to describe new species based upon minor or inconsequential morphological characters and without apparent reference to related taxa found outside of China. This is clear from recent monographic studies that compared Chinese taxa with taxa throughout the world.
Fissidens in the Neotropics
(1990)
The land areas of the Western Hemisphere south of the United States support over 276 species of Fissidens (Wijk et al. 1962, 1969). This number is approximately 30% of the total number of species known. Progress made on a monograph of the family in the neotropics and the adjacent areas is summarized; approximately 50% of the species have been studied. Commonality among the neotropical, African and Asian species of Fissidens is discussed. Changes to be made in the classification of the family are indicated. New characters used in distinguishing species and the classification of the family are enumerated.
During the past 5 years intensive bryological explorations were carried out in Tanzania with special emphasize on hitherto undercollected areas (e.g. Nguru mountains, Mafia Island, unknown accesses of Mount Kilimanjaro and Meru) and on special habitats (e.g. rocky semi-desert or heath vegetation and alkaline tolerant epiphytic vegetation along the Rift Valley). These collections (above 8000 numbers) resulted in numerous records, some of them new to the African continent and at least 8 species new to science. The data point to interesting phytogeographical links and help to explain the evolution of the flora of East African volcanoes and crystalline mountains. Hitherto unknown oil bodies of more than 50 liverwort species were investigated. This paper does not give a full account of these studies but only provides examples to illustrate the above points.
A review of the status of bryological research in each of the nations, states or governmental units of southern Melanesia, Micronesia and tropical Polynesia shows the imperfect state of knowledge about the Pacific tropical islands. Best known overall are Hawaii and Micronesia with Wallis and Futuna, the Marquesas and the high mountains of Fiji seeming to be the least known potentially species rich areas. Involvement of residents from Pacific islands in botanical study and preservation of ecosystems should be encouraged by tropical bryologists.
Epiphyllous liverworts are characteristic of tropical and subtropical forests where the air is very moist. The distribution of epiphyllous liverworts is primarily in the tropical or subtropical regions of Indo- Malay, Central and South America, central Africa and the Asian-Pacific regions of South Korea and southern Japan south to Australia. Epiphyllous liverworts are also abundant in some evergreen forests of China (Cao & Be, 1988; Chen & Wu, 1964; Wu & Guo, 1986; Wu & Lou 1978; Wu et al., 1983). Little has been known about the liverworts in Sichuan Province of China. Only eight species and one variety, belonging to eight genera have been reported from Mt. Emei (Wu & Lou, 1978) and some scattered records from Mt Erlang, Mt Yaan and Mabin County.
A project dealing with the hepatic and moss floras of New Guinea and the Solomon Islands has proceeded more than halfway. The revision of the flora is based on the study of ca 17000 specimens collected in 1981. Two new genera and ca 50 new species have been described in 33 published papers and seven manuscripts. Many families, genera and species not previously recorded for the area have been added to the flora. More than 300 names have been reduced to synonyms. The percentage of endemic species of liverworts (40 %) is higher than that of mosses (18 %). Most of the endemic species occur at elevations above 1700 m. The geological history of New Guinea suggests that these high altitude endemics may be relatively young, i.e. less than 10 million years old. The moss flora is more closely related to the floras of Indonesia and the Philippines and continental Asia than to that of Australia. This can be explained by plate tectonics. The altitudinal distribution of hepatic and moss floras partly coincides with the zonation of vegetation proposed earlier. Human influence on bryophyte floras is devastating but a part of the flora may survive in gardens and plantations.
China is located in eastern Asia, between 18°-55°N and 74°-138°E. The total land area of about 9,600,000 km is divided into 30 administrative areas. The climate varies from subtropic in the south to temperate in the north. The topography is complex. All of the conditions mentioned above cause the bryoflora to be complex. There are estimated to be about 2,000 species of Musci and 1,000 species of Anthocerotae and Hepaticae. The late Professor P.C. Chen considered that China could be divided into seven distributional areas, this view is supported by most Chinese bryologists today.
The South American paramos appeared in Pliocene times and persist to the present day. The moss flora of this habitat consists of an estimated 400 species that comprise 8 floristic groups. In Venezuela these groups and their percent representation are as follows: neotropical 37%, Andean 26%, cosmopolitan 18%, Andean-African 8%, neotropical-Asiatic 3%, neotropical-Australasian 2%, temperate Southern Hemisphere 2% and northern boreal-temperate 2%. Acrocarpous taxa outnumber pleurocarps by nearly 3:1. The neotropical and Andean floristic stocks likely were present prior to late Pliocene orogenies that elevated the cordillera above climatic timberlines. These species may have existed in open, marshy areas (paramillos) or may have evolved from cloud forest ancestors. Taxa of northern boreal- temperate affinities, including those with Asiatic distributions, probably arrived in the paramos during the Pleistocene, a period which may also have seen the establishment in the Northern Andes of some cosmopolitan elements. Species with temperate Southern Hemisphere and Australasian affinities likely spread first to austral South America thence migrated northward during a cool, moist interval sometime over the past 2.5-3 million years or may have become established in the paramos as a result of long- distance dispersal.
The Guianas (French Guiana, Suriname, Guyana) are probably one of the last areas of the world covered largely by virgin lowland rain forest. Species diversity of epiphytic bryophytes was investigated in dry evergreen forest and mixed forest using mountaineering techniques to ascend into the canopy. The results indicate that the lowland rain forest is richer in species than previously believed due to neglect of the canopy flora, which may hold more than 50% of the local species. The mixed forest holds the richest flora and on one single forest tree up to 67 bryophyte species were found (50 on average); 28 trees yielded 154 species. A species/area curve indicates that epiphytic bryophyte species are usually commonly distributed in the forest and a few trees may yield much of the local flora. A recent checklist of the Guianas includes over 600 species of bryophytes: 375 Hepaticae and 234 Musci. As the region lacks in altitude (except on Mt. Roraima) the general character of the bryophyte flora of the Guianas is typically lowland neotropical. Over 80% of the species are rather widespread in tropical America (Amazonian species included), and the remaining are Guayana Highlands, northern Amazonian or Caribbean elements. Endemism is very low: 2.5 %.
The Frullania taxa on Mount Albert Edward, Papua New Guinea, form many associations that suggest a high degree of niche similarity, but at different altitudes, different associations form. The species diversity of the genus is greatest at the middle altitudes and least in the dry lowlands. This altitudinal separation is apparent in the niche widths of the taxa. The members of the four sibling taxa pairs examined exhibit distinct altitudinal niches, suggesting that the sibling taxa are distinct, with different niche optima.
Campylopus with nearly 200 revised species is one of the largest genera of mosses in the world and has extremely broad geographical, altitudinal and ecological ranges. Factors to be considered for the rich speciation are 1) the enormous anatomical plasticity of the structure of the costa, 2) the ability for vegetative propagation utilizing different methods, and 3) the special twist mechanism of the cygneous setae. Phytogeographical interpretations of present ranges of species of Campylopus lead to the conclusion that this genus is of Gondwanalandic origin. Most of the species seem to be cool temperate in origin. They have adapted to dry habitats in the Mesozoic and invaded the tropical mountains during the Tertiary, accompanied by rich speciation. This is supported by the physiology of these species. According to preliminary gas exchange measurements, tropical montane species do not differ from temperate species, and are not able to stand climatic conditions of the tropical lowland rainforests; a relatively young habitat for bryophytes. A cladistic analysis of the infrageneric categories of Campylopus using phytogeographical evaluations of apomorphic character states shows that the section Homalocarpus seems to be the most primitive and the subgenera Campylopidulum and Thysanomitrion the most derived.
The study is based on the major part of the bryophyte material collected during the Koponen-Norris expedition on the Huon Peninsula, Papua New Guinea, in 1981. Only taxa which were collected at least twice are included. Five altitudinal zones, the boundaries of which are indicated by discontinuities in the bryophyte flora, are distinguished: 0 - 300 m, 300 - 1200 m, 1200 - 2200(-2300) m, 2200(-2300) - 2800(- 2900) m, and 2800(-2900) -3400 m. These zones, each characterized by a typical species assemblage, are well in accordance with some earlier New Guinean zonation schemes based on the phanerogamic flora and vegetation. The most obvious correlations between bryophytes’ altitudinal ranges on the Huon Peninsula and their general phytogeography are: New Guinean or Western Melanesian endemics, as well as Malesian endemics, are concentrated at relatively high altitudes (zones III-V); Asian - Oceanian and Asian - Oceanian - Australian taxa, notably mosses, are relatively strongly represented at low to moderate altitudes (zones I-III); species which have their main distribution in the northern hemisphere occur at high altitudes; 'cosmopolitan' species either have wide vertical ranges or are restricted to high altitudes.
The growth habit of the Hedwigiaceae has been described variously as acrocarpous, pseudopleurocarpous, or pleurocarpous. Anatomical evidence presented here indicates that Hedwigia ciliata is acrocarpous. The archegonia are terminal on the main shoot, and the branching pattern is sympodial. The main axis of each plant thus consists of a succession of subterminal innovations, rather than a single shoot of indeterminate growth. Since the plants are plagiotropic and are pleurocarpous in appearance, this growth pattern can be also called pseudo-pleurocarpous.
Advances in Mexican bryology
(1990)
The distinctions between dispersal and vicariance are discussed and shown how they relate to geological history. Postulated theories on the tectonic origins and history of the Greater Antilles are reviewed, as well as possible climatic events that would affect biogeography. Numerous zoological examples are presented to argue both dispersalist and vicariance viewpoints. It is proposed that the modern moss flora of the Greater Antilles is best explained primarily by dispersal events. Post-vicariant events, such as Pleistocene climate changes, would have extirpated the vast majority of mosses from the islands and even among those taxa that survived, disperal by the same taxa would have obscured their origins. It is assumed that many of the North American elements in the high elevations of Hispaniola are a result of invasions during the Pleistocene. The Andean elements are considered relatively recent dispersally derived taxa that have successfully colonized the Antilles because of ecologically compatible habitats.
Crossomitrium is a genus of neotropical, essentially epiphyllous mosses. The genus consists of six species that are distributed in two sections: section Crossomitrium (C. acuminatum, C. patrisiae, and C. scabrisetum) and section Cormophila (C. epiphyllum, C. saprophilum, and C. sintenisii). Section Crossomitrium is characterized by 1. plants nearly always on leaves or twigs, 2. lateral leaves oblongacuminate and widest below the middle, 3. leaves when dry that arch from an erect base downward to the substrate and, 4. the presence of specialized brood branches that are closely adnate to the substrate and have tightly imbricate leaves. Section Cormophila is characterized by 1. plants growing on rocks and tree trunks as well as on leaves, 2. lateral leaves oval to obovate, acute to apiculate and widest above the middle, 3. leaves when dry flattened to the substrate and, 4. the presence of erect, specialized brood branches that have leaves spreading on all sides. Crossomitrium is placed in the Hookeriaceae (sensu Whittemore & Allen, 1989) on the basis of its branched stems, ecostate leaves, straight, unbranched rhizoids that are tightly clustered just posterior to the leaf bases, 2-celled axillary hairs and weakly pigmented stem cortex. Within the Hookeriaceae Crossomitrium is considered close to the genus Lepidopilum by virtue of 1. its peristome which is hydrocastique and has a high basal membrane, 2. the spinose setae of C.acuminatum and C. scabrisetum, 3. the irregular subdivision of its stomatal guard cells (including the presence of stomates at the base of raised pustules), 4. leaves doubly serrulate by the projecting ends of contiguous marginal cells, 6. absence of a stem central strand. It differs from Lepidopilum in its 1. symmetric, ecostate leaves, 2. calyptra fimbriate by downward projecting, multicellular hairs that arise from the margins of the calyptra, 3. collenchymatous exothecial cells, 4. the presence of broodbodies on specialized brood branches as well as in clusters just below the junction of the leaf with the stem.