Myxomycetes & Other Slime Molds
|
Arcyria cinerea  Click photo to enlarge. Photo by Randy G. Darrah. |
Myxomycete plasmodia typically occur in cool, moist, shady places such as within crevices of decaying wood, beneath the partially decayed bark of logs and stumps, and in leaf litter on the forest floor. Under favorable conditions, the plasmodium gives rise to one or more fruiting bodies containing spores. The spores of myxomycetes are for most species apparently wind-dispersed and complete the life cycle by germinating to produce the uninucleate amoeboflagellate cells.
The fruiting bodies produced by myxomycetes are somewhat suggestive of those produced by higher fungi, although they are considerably smaller (usually no more than 1-2 mm tall). Although large enough to be seen with the naked eye, they are best observed with a hand lens or under a stereomicroscope. Only then can their intricate nature be fully appreciated. Fruiting bodies may take the shape of tiny goblets, globes, plumes, or other shapes more difficult to describe. Some occur in tightly packed clusters, while others are scattered or even solitary. Many of the more intricate forms have a spore case held aloft on a delicate stalk, but others are attached directly to the substrate by their bases.
There are approximately 875 recognized species of myxomycetes. The majority of species are probably cosmopolitan, but a few species appear to be confined to the tropics or subtropics and some others have been collected only in temperate regions. Myxomycetes appear to be particularly abundant in temperate forests, but at least some species apparently occur in any terrestrial ecosystem with plants (and thus plant detritus) present. Most of what is known about the assemblages of myxomycetes associated with particular types of terrestrial ecosystems has been derived from studies carried out in temperate regions of the northern hemisphere. In these forests, myxomycetes are associated with a number of different microhabitats. These include coarse woody debris on the forest floor, the bark surface of living trees, and forest floor leaf litter. Each of these microhabitats tends to be characterized by a distinct assemblage of myxomycetes.
Prior to the beginning of the ATBI, 92 different species of myxomycetes had been reported from the Park, and the majority of these records were based upon specimens collected more than a half century ago. As a result of collecting carried out in the context of the ATBI, more than 120 species have been added to this total. The most surprising finds are four species of myxomycetes not previously known from North America and two others that appear to be new to science. However, it is anticipated that there are many more species to be found. In fact, based upon the results obtained thus far, the Great Smoky Mountains National Park appears to be one of the world's "hot spots" for myxomycetes, with as many species present in the Park as anywhere else on earth.
Visit the Tree Canopy Biodiversity page for information on myxomycete diversity in the tree canopy of the Great Smoky Mountains National Park .
The myxomycetes are actually just one of three groups of organisms to which the name "slime mold" has been applied, and the inventory currently underway in the Park also includes these other slime molds--the dictyostelids and protostelids. Members of both groups are so small that they are virtually impossible to observe directly in the field. Instead, surveys for dictyostelids and protostelids are carried out in the laboratory by culturing these organisms from various types of organic material brought in from the field.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Taxonomic Category |
Scientific Name |
Common Name |
Kingdom |
Mushrooms & Molds |
