Dictyostelium mucoroides from subantarctic Macquarie Island

Abstract

During the period of early February to early April of 1995, samples for isolation of dictyostelid cellular slime molds were collected from representative examples of all major types of plant communities found on subantarctic Macquarie Island. These included tussock grassland, short grassland, herbfield, fernbrake, mire, and feldmark communities. There are apparently no previous reports of dictyostelids from the south polar region, but Dictyostelium mucoroides was recovered from soil/litter and/or recovered from soil/litter and/or litter samples collected in tussock grassland, herbfield, and fernbrake communities. Densities were almost invariably low (<50 colony-forming units/g), but one study site yielded 135 colony-forming units/g. The most diverse plant communities on Macquarie are mixed herbfield communities that occur on raised coastal terraces, and the majority of positive samples were collected from these communities. No dictyostelids were recovered from samples collected at higher elevations (generally >200 m) on the main plateau of the island. In general, both frequency of occurrence and density were higher for samples of moist, decomposing litter found around (and sometimes still attached to) the bases of such plants as Pleurophyllum hookeri and Stilbocarpa polaris than for samples collected from the soil/litter interface zone.