Cellular slime molds in tundra and forest soils of Alaska including a new species, <i>Dictyostelium septentrionalis</i>

Abstract

The occurrence and distribution of cellular slime molds in Alaska were investigated. Particular emphasis was given to tundra soils since this habitat was not previously explored for cellular slime molds. Isolations were also made from the white spruce – aspen forest of the interior forest region and the western hemlock – Sitka spruce forest of the southeast coastal forest region. Three species Dictyostelium mucoroides, D. sphaerocephalum, and D. giganteum occur in tundra. The first two species are common and frequently very abundant indicating that cellular slime molds play an active role in tundra ecology. Six other species were found in forest soils. One, Dictyostelium septentrionalis, was found for the first time and is described as a new species. It is distinctive for its size and optimum growth temperature, which is below 20 °C. The study completes the investigation of the latitudinal distribution of cellular slime molds in the northern hemisphere, establishing their occurrence north of the Arctic Circle.