Cyathus stercoreus
Description
Cyathus stercoreus is a species of fungus in the genus Cyathus, family Nidulariaceae. Like other species, the fruiting bodies of C. stercoreus resemble tiny bird nests filled with eggs. The fruiting bodies are referred to as splash cups because they are developed to use the force of falling drops of water to dislodge and disperse their spores.
This mushroom has a worldwide distribution, and prefers growing on dung, or soil containing dung; the specific epithet is derived from the Latin word stercorarius, meaning "of dung".
Common names: Splash-Cup Bird's-Nest, Dung-Loving Bird's-Nest Fungus, Dung Bird's Nest.
Mushroom Identification
Ecology
Saprobic; growing gregariously or in dense clusters on wood chips, organic debris (straw, sawdust, and so on), manured soil, or dung; summer and fall (or overwinter in warm climates or greenhouses); widely distributed in North America.
Nest
Typically about 1 cm high and a little less than 1 cm wide at the top; goblet-shaped; outer surface brown to reddish-brown, hairy and shaggy when young (but sometimes becoming smooth with age); inner surface bald and shiny, dark brown to black; "lid" typically whitish, soon disappearing.
Eggs
To 1 or 2 mm wide; lens-shaped; attached to the nest by cords—but the cords can be very difficult to find, especially for the eggs near the top of the pile.
Microscopic Features
Spores extremely variable in shape and size, but generally quite large (18–40 x 18–30 µm); globose to oval; smooth; thick-walled.
Cyathus stercoreus Ultrastructure
Examination of fruiting bodies using scanning electron microscopy and transmission electron microscopy has revealed details about their ultrastructure—their microscopic architecture and arrangement.
For example, the hyphae of the hapteron form a dense tangled network, while the hyphae of the funicular cord are arranged in a twisted form like a rope. Further, the funicular cord, known to be highly elastic and with a high tensile strength, is made of thicker hyphae than the rest of the funiculus.
Also, the ecto- and endoperidium are made of thick-walled, unbranched hyphae, known as skeletal hyphae. It has been proposed that these skeletal hyphae form a structural network that helps the fruiting body maintain the elasticity vital for proper functioning of the spore dispersal mechanism.
Life Cycle
The life cycle of Cyathus stercoreus, which contains both haploid and diploid stages, is typical of taxa in the basidiomycetes that can reproduce both asexually (via vegetative spores), or sexually (with meiosis). Basidiospores produced in the peridioles each contain a single haploid nucleus.
After dispersal, the spores germinate and grow into homokaryotic hyphae, with a single nucleus in each compartment. When two homokaryotic hyphae of different mating compatibility groups fuse, they form a dikaryotic (containing two nuclei) mycelia in a process called plasmogamy.
After some time (approximately 40 days when grown from the pure culture in the laboratory) and under the appropriate environmental conditions, fruiting bodies may be formed from the dikaryotic mycelia. These fruiting bodies produce peridioles containing the basidia upon which new basidiospores are made. Young basidia contain a pair of haploid sexually compatible nuclei that fuse, and the resulting diploid fusion nucleus undergoes meiosis to produce haploid basidiospores.
Cyathus stercoreus Spore Dispersal
When a drop of water hits the interior of the cup at the appropriate angle and velocity, the peridioles are ejected into the air by the force of the drop. The force of ejection tears open the purse, and results in the expansion of the funicular cord, formerly coiled under pressure in the lower part of the purse.
The peridioles, followed by the highly adhesive funicular cord and basal hapteron, may hit a nearby plant stem or stick.
The hapteron sticks to it, and the funicular cord wraps around the stem or stick powered by the force of the still-moving peridiole. After drying out, the peridiole remains attached to the vegetation, where it may be eaten by a grazing herbivorous animal, and later deposited in that animal's dung to continue the life cycle.
Cyathus stercoreus Bioactive Compounds
Several polyketide-type antioxidative compounds, cyathusals A, B, and C, and pulvinatal have been isolated and identified from the liquid culture of Cyathus stercoreus. Furthermore, the polyketides known as cyathuscavin A, B, and C (isolated from liquid culture) also have antioxidant activity and have DNA protection activity.
Photo sources:
Photo 1 - Author: Kiloueka (Public Domain)
Photo 2 - Author: Kiloueka (Public Domain)
Photo 3 - Author: Iskra Kajevska (CC BY-SA 4.0)