Physarum bitectum

Physarum bitectum G. Lister in Lister, Mycet. ed. 2. 78. 1911
Physarum Diderma sensu Lister, Jour. Bot. 29: 260. 1891. Not P. Diderma Rost. 1874.
Sporangiate, sessile, subglobose, 0.6-0.8 mm. in diameter, or forming short, usually unbranched plasmodiocarps up to 6 mm. long, smooth, white or pallid, terete or somewhat compressed; peridium double, the outer wall calcareous, free, deciduous above, recurved and persistent below, the inner smooth, pale purple, persistent; dehiscence irregular, by the breaking away of the upper part of the peridium; capillitium of large, white nodes connected by short, hyaline tubes; spores black in mass, dark violaceous-brown by transmitted light, spinulose, with a conspicuous smoother area, 10-13 p in diameter.
Type locality: Great Britain. Habitat: Dead leaves and twigs.
Distribution: Ohio to Washington (state), south to Kansas and California, and in Puerto Rico; South America; Europe; South Africa; Australia.