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NEW YORK SPECIES To date, research on slime molds in New York has centered around the collections of just a few researchers. Robert Hagelstein, who lived and collected on Long Island, provided the most comprehensive, albeit geographically restricted, body of data on the myxomycetes (Hagelstein, see section on myxomycetes), while research on dictyostelids (Cavender and Raper 1965a) and protostelids (Olive and Stoianovitch 1969) is limited and haphazard at best. The published information documents species present in New York, but offers no quantitative data for any specific physiographic region in the state. As a result, it is unknown whether there are hotspots for these organisms. The ecological data necessary to make determinations of the introduction of invasive species, number of extirpated, extinct, and endemic species are not available. Even though the ecology of these organisms is better understood now than just 10 years ago, it is still in its infancy. Currently, 175 myxomycete species, 5 dictyostelid species, and 2 protostelid species have been recorded for the state (Table 1). Myxomycetes
The myxomycetes, commonly called the plasmodial or acellular slime molds, are characterized as having a feeding phase represented by a multinucleate plasmodium. This plasmodium sporulates to produce a fruiting body with spores, which are transported by wind as well as by various animals, especially microarthropods. Myxomycete trophic cells and fruiting bodies occur on leaf litter, twigs, dead and living trees, and dung. They may be sampled from nature by collecting fruiting bodies, which are usually one to a few millimeters in size, directly from a substrate. Alternatively, the substrates can be placed into a moist chamber created by a petri plate and wet filter paper. Within a few days to a few weeks, fruiting bodies appear on substrates in the moist chambers. Species are identified by the type and internal structure of the fruiting body. Though primarily terrestrial, some myxomycetes have been found in aquatic habitats and associated with snowbanks (Stephenson and Stempen 1994). Biogeographical studies have revealed that habitat type appears to strongly influence species distributions of myxomycetes. When comparing two similar habitat types, the species composition is similar regardless of the distance between the habitats (Stephenson 1988; Stephenson et al. 1993). However, when comparing different habitat types, species assemblages of myxomycetes are dissimilar between sites (Alexopoulos 1970; Blackwell and Gilbertson 1980; Stephenson et al. 1993). As with other organisms, some species are widely distributed and occur in numerous habitat types, while other species are absent or rare in some habitats but abundant in others. Microhabitat studies on myxomycetes are somewhat limited. Studies have focused primarily on species associated with decaying wood or bark of living trees (Keller and Brooks 1973, 1977; Martin and Alexopoulos 1969), although a number of other microhabitats commonly have myxomycetes associated with them. Stephenson (1989) concluded that myxomycetes exhibit differential distribution in temperate habitats and that species common in one microhabitat are not common in another. The research on New York slime molds primarily consists of the work of Hagelstein (1927, 1929, 1930, 1935a, 1935b, 1936, 1937, 1938, 1939, 1940, 1942, 1943) who collected myxomycete fruiting bodies directly from substrates at various localities on Long Island. As a result, the majority of current taxonomic lists are based on his collections of fruiting bodies from southeastern New York. More recently, research by Binion (2001) investigated myxomycetes from the Catskills/New York City watershed. Two species were new records for New York. Dictyostelids
Dictyostelids live primarily in soil, humus, and dung. Sampling for dictyostelids consists of collecting samples of these substrates from nature, preparing a dilution of the sample, and plating this onto a petri plate. After a short incubation period, usually three or four days, fruiting bodies with numerous spores are present and may be observed with a dissecting microscope. Identification is based on type of fruiting body and spore characteristics (Raper 1984). Dictyostelid spores are packaged as a slimy spore mass that appears to be well-suited for dispersal by microarthropods, mammals, and birds (Feest 1987; Suthers 1985). Biogeographical studies of dictyostelids suggest species composition is similar between similar habitat types (Cavender 1969, 1980, 1983; Cavender and Raper 1965a, b; Cavender et al. 1995), and different between different habitat types (Cavender 1969, 1973, 1976, 1978; Cavender and Kawabe 1989; Vadell et al. 1995). Dictyostelids are widely distributed, occurring in numerous habitat types, while other species are absent or rare in some habitats but abundant in others. Microhabitat studies of dictyostelids are somewhat limited. Dictyostelids have been documented to inhabit dung, soil, and decaying organic matter (Olive 1975; Raper 1984). Unlike the myxomycetes, no species appear to be confined to a particular microhabitat, but no specific studies have addressed this question. The research on New York dictyostelids is limited to the studies of Cavender and Raper at Cranberry Lake, a site in St. Lawrence County (Cavender and Raper 1965a). As most dictyostelid species appear to be cosmopolitan, several more records would likely be produced if collections were made in other localities throughout the state. Protostelids
The protostelids are the simplest of all the slime molds, and were the most recently discovered (Olive and Stoianovitch 1960). They produce microscopic fruiting bodies consisting of a simple, acellular stalk with one to a few spores at its tip. Protostelids are too small to be observed directly from nature. As a result, sampling these organisms entails collecting substrates they typically inhabit, soaking the samples in sterile water, and placing the pieces onto a weak nutrient agar medium (Olive 1975). After a few days, protostelid fruiting bodies appear on or near the pieces of material. Suitable substrates for protostelids include leaf litter, soil, bark, and dung (Olive 1975). Protostelids appear to be cosmopolitan in different habitat types, having been recorded from samples collected from almost everywhere in the world (Spiegel 1990). Research in temperate habitats compared to that carried out in tropical habitats reveals that many abundant temperate species are present in the tropics (Moore and Spiegel 2000a, b; Moore and Stephenson 1998; Stephenson et al. 1999). However, some species are rare in both habitats. For protostelids, microhabitat plays a greater role than habitat in the distribution of species (Moore and Spiegel 2000b). The standardized technique developed by Moore and Spiegel (1995) has greatly enhanced our ability to enumerate protostelids in situ on sterile straws placed into a particular microhabitat known to contain an assemblage of protostelid species. Research shows that some protostelid species are more abundant on substrates collected from the aerial litter microhabitat when compared to the forest floor litter microhabitat. Conversely, other species are present, and more abundant, on substrates from the forest floor litter microhabitat (Moore and Spiegel 2000b). As with the other groups of slime molds, the protostelids have been studied in areas where individuals who work with the group live or like to travel. Current published research is confined to the work of Lindsay Olive (1969), although his field notes may reveal more species. As with the dictyostelids, several protostelid species are probably very abundant in the state, but the documentation is currently lacking. Factors affecting slime mold diversity Biodiversity studies of slime molds in the United States, the tropics, and various locations in the Southern Hemisphere suggest that slime molds are abundant, that some species are specialists (either to substrate or ecosystem type), and that biodiversity changes across latitude and altitude. Environmental factors such as temperature and moisture have been shown to play a defining role in their distributions. Research on slime molds in New York has been confined to Long Island, the vicinity of Cranberry Lake in St. Lawrence County, and the Catskills area of the New York City watershed. If slime molds were quantitatively studied in New York State, similar patterns would likely be revealed. Unfortunately, the greatest factor limiting what we know about their biodiversity is the very low number of researchers investigating them. Current ecological studies are limited, globally and locally. Although the ecological studies have increased over the past 40 years, they are still severely lacking.
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