Sarcosoma globosum (Schmidel) Rehm
A Cup Fungus
Basis for Listing
Sarcosoma globosum (a cup fungus) is a large distinctive cup fungus that is known from a single location in Minnesota: Johnson Lake, Superior National Forest, St. Louis County (Border Lakes Subsection). It is reported as being distributed from the Upper Great Lakes region east to New England, and adjacent Canada (Smith et al. 1981), with occasional reports from Virginia and North Carolina, Washington, Oregon, Idaho, and Montana. It is considered rare both in North America (Smith et al. 1981; Bessette et al. 1997) and Europe, where the European Council for Conservation of Fungi has proposed it for listing under the Bern Convention (Dahlberg and Croneborg 2003). In 2013, it was classified as a special concern species in Minnesota because it has only a single known location in the state.
Sarcosoma globosum is a large distinctive species forming a tall dark brown gelatinous cup (Seaver 1961; Smith et al. 1981). The fruiting body is 4-10 cm (1.6-3.9 in) broad when mature and 7 cm (2.8 in.) tall. It is globose when young and becomes flattened to depressed on the upper surface, forming a cup 1 cm (0.4 in.) deep as the spore-forming layer forms, and it bulges out below. Externally, the fruiting body is brownish-black with a tough outer surface; internally, it is watery and gelatinous. Spores are ellipsoid, hyaline, smooth, and thin-walled, averaging 27.5 by 9.6 µm. They are produced in the cup in very long asci, mostly 310-335 µm by 14-17 µm, which are surrounded by narrow brown filaments, 4 µm wide.
In Minnesota, S. globosum was found fruiting in shaded, moist pine needle duff in a depauperate herbaceous layer under Betula papyrifera (paper birch), Populus tremuloides (quaking aspen), and Abies balsamea (balsam fir), with Pinus strobus (white pine) nearby (northern fire-dependent woodland). It has been reported fruiting on the ground in needle litter with other tree species in eastern North America including Pinus banksiana (jack pine), Picea sp. (spruce) and jack pine-spruce stands with an understory of balsam fir and white pine.
Biology / Life History
Members of the Sarcosomataceae are likely saprobic and occur on wood, other plant parts, or soil (Hansen and Pfister 2006). The temperate members of this family typically fruit in the spring.
Conservation / Management
Loss and degradation of habitat because of changes in land use are the greatest threat to the preservation of rare fungi. Sarcosoma globosum fruits in the spring; in Minnesota, it was recorded in late May. Additional surveys for this species are needed.
Best Time to Search
The best time to searh for Sarcosoma globosum is from April to June.