Cellular Slime Molds of Japan. I. Distribution and Biogeographical Considerations

ABSTRACT

Dictyostelid slime molds were isolated from forest soils of the three main islands of Japan, Honshu, Shikoku and Hokkaido. Twenty-six species were recovered, including three undescribed. Dictyostelid species richness in Japan is twice that found in Ohio or Europe while it is comparable to that of eastern North America from Key Largo, Florida to Maine. This relatively high species richness is believed to be due to a number of factors: 1) moist climate of considerable temperature range; 2) protective insular environment; 3) maintenance of much of the mountainous interior of Japan in forest; and 4) preservation of original forest remnants throughout the islands. Distribution of dictyostelid species in Hokkaido and northeastern United States is similar and has elements in common with the distribution of herbaceous and woody plant species in these regions. When the four studied temperate forest areas (eastern North America, western Himalaya Mountains of India, Europe, Japan) are compared, Japan and eastern North America are most alike in terms of dictyostelid species shared in common, but all studied areas have some species in common as well as one or more endemics.

Key Words:

• cellular slime mold distribution
• forest soil
• biogeography
• Japan