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time, the species always survives by
reestablishing itself in some new habitat (which may be indeed the very same habitat if
conditions once again become favorable). Although the spores of myxomycetes would
appear to have considerable potential for long-distance dispersal, there is little question that
some species are more common in some regions of the world than others, and the non-
availability of certain microhabitats apparently imposes major constraints upon their
occurrence even within a particular region. As such, it would seem that myxomycetes do
not necessarily conform completely to the “ubiquity of small free-living eukaryotic
species” concept as proposed by Finlay (2002) and Fenchel and Finlay (2004). The very
fragmented range of Barbeyella minutissima, a species that appears to be conWned almost
exclusively to montane Picea and/or Abies forests, provides a good example. Thus, the
myxomycete distribution data are consistent with the “moderate endemicity model”
proposed by Foissner (2006), who suggests that about 30% of the protist species are
morphological and/or genetical and/or ecological endemics.
Although at least some species of myxomycetes are very easy to recognize (for instance,
Leocarpus fragilis) and their fruitings may well assume macroscopic conditions, there is no
doubt that the distribution maps presented herein are still fragmentary. As to be expected
for organisms having a limited number of active researchers, the range of a species as
Fig. 5 Distribution map for the tropical myxomycete-like protostelid Ceratiomyxa morchella Welden
64 W. Foissner et al. (eds)
depicted on a distribution map will largely reXect those records from regions of the world
(Europe, eastern North America and Japan) where most myxomycetologists live and work.
Only recently, in the context of the Global Biodiversity of Eumycetozoans and GBIF Inter-
national projects mentioned earlier in this chapter, has a systematic digitalization of records
begun, and we estimate that fewer than 25% of all herbarium specimens worldwide have
been databased. Only the fruiting body stage of myxomycetes was considered in the devel-
opment of the distribution maps presented herein, and it is certainly possible that there are
habitats where myxomycetes live as amoebal and/or plasmodial populations only and do
not fruit. If this is the case, then a particular species could have a larger “true” distribution
than reXected by a map compiled on the basis of records of fruiting bodies. This may well
be the case for continuously moist montane rainforests, where Schnittler and Stephenson
(2000), for a study carried out in Costa Rica, detected a gradient of decreasing myxomycete
diversity with increasing elevation and rainfall. Direct environmental sampling with the use
of molecular techniques such as DNA probes would represent a way of detecting hidden
amoebal and/or plasmodial populations of myxomcyetes, which would be regarded as
“sink” populations in terms of dispersal capacities. On the other hand, especially for cortic-
olous myxomycetes such as Protophysarum phloiogenum that grow readily in substrate
cultures (this species is characterized by a developmental time between 2 and 6 days), such
“hidden” populations should be detected regularly if the appropriate survey eVorts were
carried out.
Acknowledgements A major part of the specimen digitalization work which formed the basis for the
distribution maps presented in this paper was carried out within a grant of the seed money program of GBIF
International, coordinated by the second author. Another grant funded in the context of the Global Biodiver-
sity of Eumycetozoans project (DEB-0316284) from the US National Science Foundation added data espe-
cially for the American continent. Appreciation is extended to many of our colleagues for providing additional
information on records of particular species. Among these are G. Adamonité (Lithuania), U. Eliasson
(Sweden), A. Estrada-Torrez (Mexico), A. Koshelova (Russia), C. Lado (Spain), R. McHugh (Ireland), M.
Meyer (France), D. Wrigley de Basanta (Spain) and I. Zemlianskaya (Russia). We also wish to thank John
Shadwick for helping produce the distribution maps of the four species.
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