Foissner_Protist Diversity and Geographical Distribution_9048128005

fruiting along the margins of melting snowbanks in late spring and early
summer. The species that occupy this rather special and very limited habitat are usually
58 W. Foissner et al. (eds)
referred to as “snowbank” or “nivicolous” myxomycetes. They constitute a distinct ecolog-
ical group, since they usually produce fruiting bodies only during the relatively brief period
of time when the special microenvironmental conditions associated with margins of
snowbanks and apparently required for their growth and fruiting exits. During the remain-
der of the summer, the species of myxomycetes found in these alpine areas are very much
the same as those collected at lower elevations in the same regions. Interestingly, the
majority of species in some genera tend to be predominately alpine in distribution. This is
true for Dianema (Kowalski 1967), Lamproderma (Kowalski 1970), and Lepidoderma
(Kowalski 1971).
Long-distance dispersal
It has long been recognized that various small particles, including dust, spores, bacteria and
other microbes, can be carried long distances by wind. For example, the British mycologist
Berkeley (1857) concluded that “The trade winds, for instance, carry spores of fungi mixed
with their dust, which may have traveled thousands of miles before they are deposited.” In
the mid-1930’s, Meier (Meier and Lindbergh 1935) identiWed a variety of fungal spores,
pollen, algae and diatoms from a series of samples collected over the North Atlantic by
exposing sterile, oil-coated microscope slides directly to the air by way of a long metal arm
extending from an airplane. A process that could transfer enormous numbers of microor-
ganisms into the atmosphere was identiWed in the late 1990’s, when satellite images
revealed the astonishing magnitude by which desert soils are aerosolized into giant clouds
of dust (GriYn et al. 2001, 2002; Kellogg and GriYn 2006). These clouds of dust fre-
quently move across the Atlantic Ocean and reach the Caribbean, Central America, north-
ern South America and the southeastern United States, where the particles they contain
(including spores) are deposited. Amazingly enough, it has been demonstrated that plants
living in the upper canopy of rainforests in South America actually derive a major portion
of their nutrients from this dust fallout (Swap et al. 1996). Similar long-range movements
of dust have been demonstrated for other parts of the world, including from Asia across the
PaciWc Ocean to western North America and from Australia to New Zealand. One particu-
larly large dust cloud originating in China actually moved eastward all the way across the
PaciWc, North America and the Atlantic to reach Europe, thus traveling most of the way
around the world (GriYn et al. 2002). Clearly, airborne spores would have the potential of
being dispersed by wind over considerable distances. Muñoz et al. (2004), who evaluated
the possible role that wind might play in long-distance dispersal of mosses, liverworts,
lichens, and pteridophytes among land masses in the Southern Hemisphere, found that
Xoristic similarities were more strongly correlated with global wind patterns than geo-
graphic proximity. For the most part, the land masses considered in this study were the
small, rather isolated islands in the Southern Ocean, for which the groups of organisms
being considered are well documented. The results reported in this study would seem to
lend support for the idea that myxomycetes could have reached these same islands as a
result of long-distance dispersal by wind, and the data available for one of the islands,
Macquarie Island located south of Tasmania, indicate that the island is characterized by a
relatively diverse myxoXora (Stephenson et al. 2007). In the same way, a diverse assem-
blage of myxomycetes occurs on the isolated Hawaiian Islands (Eliasson 1991).
If the spores of myxomycetes are largely wind-dispersed, as is generally considered to
be the case (Alexopoulos 1963), then the global wind patterns noted above would give
them considerable potential for long-distance dispersal over intercontinental distances.
Protist Diversity and Geographical Distribution 59
However, it is possible that long-distance dispersal by wind may not be as common for
myxomycetes as one might suspect. Although most myxomycetes are thought to have very
large distributional ranges and many species appear to be cosmopolitan or nearly so, results
from recent studies (e.g., Stephenson et al. 1993) have provided evidence that spatial distri-
bution patterns of these organisms can be successfully related to (1) diVerences in climate
and/or vegetation on a global scale and (2) the ecological diVerences that exist for particu-
lar habitats on a local scale. To demonstrate that myxomycetes have recognizable distribu-
tion patterns in spite of the theoretical ability of their spores to bridge continents, the global
distribution of four species will be assessed and then discussed in the section that follows.
These four species are Barbeyella minutissima, Ceratiomyxa morchella, Leocarpus fragilis
and Protophysarum phloiogenum.
Examples for myxomycete distribution patterns
The four species being considered are (1) very diVerent in their ecology, (2) taxonomically
distinct and thus unlikely to be confused with any other species, and (3) display microhabi-
tat preferences that are suYciently well known to allow them to be detected during the
course of biodiversity surveys of the myxoXora of a particular region. The records upon
which our analyses are based have been Wltered out of a body of more than 100,000 digital-
ized records of myxomycetes, encompassing the resources of the Global Biodiversity
Information Facility (GBIF, http://www.secretariat.gbif.net/portal/index.jsp), the database
of the Eumycetozoan Project based at the University of Arkansas (http://slimemold.
uark.edu), several major herbarium collections (Beltsville/BPI, Toronto/TRTC, Ottawa/
DAOM, Munich/M, St. Petersburg/LE, Madrid/MA-Fungi (see Pando et al. 2003)), and the
private collections of a number of individuals, including the authors.
Barbeyella minutissima Meyl. (Echinosteliales) is a minute but very distinct myxomy-
cete described in 1916 from the Swiss Yura Mountains. As a result of their conspicuous
black color, which stands out in sharp contract to the substrate upon which they usually
occur, the 0.4–0.9 mm tall sporocarps can be detected in the Weld; only rarely has the
species been reported to occur in moist chamber culture. In one of the Wrst studies of the
distribution pattern of a particular species of myxomycete, the biogeography of
B. minutissima was discussed in detail by Schnittler et al. (2000). Herein, we present an
updated distribution map compiled from 123 records (Fig. 2). This species shows a strong
preference for slimy, algae-covered and decorticated logs and seems to develop only
in situations providing continuously high humidity but sheltered from direct rainfall. A
good indicator for the presence of B. minutissima seems to be lignicolous occurrences of
the liverwort Nowellia curvifolia (Dicks.) Mitt. (Stephenson and Studlar 1985). Virtually
all records are from boreal and montane coniferous forests, especially Picea and/or Abies
forests (Schnittler et al. 2000; Stephenson 2004). One exception represents a record from a
moist chamber culture of Malus bark collected in the upper Rhine valley (Neubert et al.
1993), were spores of the species could have come from the adjacent Black Forest. The
range of B. minutissima seems to be very fragmented, but repeated Wndings on the high
volcanos in Mexico (the species appears to be quite common in the Abies forests near the
summit of the Malinzi Volcano in the state of Tlaxcala (A. Estrado-Torrez, pers. comm.))
seems to provide evidence of eVective dispersal by air-borne spores.
The minute myxomycete Protophysarum phloiogenum M. Blackw. and Alexop. is the
only member of a monotypic genus, described by Blackwell and Alexopoulos (1975), that
is assumed to