Slime Molds of New York State
Table of Contents
	Table of Contents	New York Species

INTRODUCTION

Photo of Myxomycete species: Physarum viride

In New York and worldwide, little is known about the ecology of the slime molds, especially when compared with what is known about the avifauna, angiosperms, and fungi. What is known is that the slime molds are a group of eukaryotic organisms that produce fruiting bodies with spores and have an amoeboid feeding cell during their life cycle (Olive 1975; Spiegel et al. 1995). They are phagotrophic bacteriovores that are present, and often abundant, on or in decaying plant material and soil in terrestrial decomposer ecosystems throughout the world. It is hypothesized that they are important regulators of microorganism populations in these ecosystems (Feest 1987). The slime molds are composed of three distinct groups: the myxomycetes, dictyostelids, and protostelids, or plasmodial, cellular, and unicellular slime molds, respectively. They differ in the complexity and type of trophic cell and fruiting body in their life cycles. In the current classification of the slime molds, as proposed by Spiegel (1995), a single phylum-Eumycetozoa-is recognized, with two subphyla, the Protostelia, and the Myxogastria. The dictyostelids are currently at the taxon level of order, Dictyostelia, because this is the lowest taxon level that contains all dictyostelids. Even though some species exhibit restricted distribution, most species appear to be cosmopolitan. Currently, there are fewer than 800 described species in the world. Research of slime molds in New York State is severely lacking, with only 182 documented species.

The depth of knowledge of each group of slime molds is related to the number of years in which scientists have been investigating them. The slime molds are fairly new to science, with the first example, a myxomycete, described in the 1700s by Linnaeus (D.W. Mitchell, pers. comm.). The first dictyostelid was described in 1869 (Brefeld 1869), and the protostelids were not discovered until 1959 (Olive and Stoianovitch 1960). A significant amount of information is known about the basic biology of each group, including life cycle descriptions, ultrastructure of feeding cells, and fruiting body development (Martin and Alexopoulos 1969; Olive 1975; Raper 1984; Stephenson and Stempen 1994). Knowledge of their ecology, however, is severely lacking. Currently, fewer than 20 people in the United States actively study these organisms. As a result, our knowledge of their ecology is centered around where these individuals carry out their research.

The ecological study of slime molds began with simple lists of slime molds from various localities. During the last 40 years, researchers of slime molds began developing techniques to quantify the number of slime molds present in various habitats (see Cavender and Raper 1965; Eisenberg 1976; Feest 1987; Feest and Madelin 1985a, b; Moore and Spiegel 1995). Studies indicate some consistencies in protostelid, myxomycete, and dictyostelid ecology (Stephenson et. al. 1999). Temperature and moisture have been shown to be the primary factors influencing seasonal distribution (Cavender and Raper 1965a; Feest and Madelin 1988a, b; Kuserk 1977; Raper 1984; Stephenson and Stempen 1994), while relative abundance of food appears to regulate myxomycete and dictyostelid populations (Feest and Madelin 1988a; Kuserk 1980; Raper 1984; Turner 1978). All three groups of slime molds tend to prefer certain types of substrates, although quite differently. Protostelids and myxomycetes occur on decaying plant parts, bark, soil, humus, and dung, while dictyostelids are confined to soil and dung. There also appears to be an effect of latitude on slime mold biodiversity. Species richness in all three groups of slime molds seems to decrease with increasing latitude (Moore and Spiegel 2000a; Stephenson et al 1999), but only the dictyostelids seem to achieve their highest biodiversity in the tropics (Cavender 1973; Raper 1984; Stephenson et al. 1999). Species of slime molds have cosmopolitan examples and rare examples, both locally and globally (Kawabe 1980; Olive 1975; Raper 1984; Stephenson and Stempen 1994).

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