Dacrymyces stillatus Nees 1816

The species was originally discovered by Nees (1816) and described by Fries (1921), when the genus’ name was changed from Dacryomyces to Dacrymyces. Fries described the fruiting body as gelatinous, homogeneous, and composed of ascending, interwoven filaments with spores born on all sides of the fructification, or fruiting structure.

D. stillatus has two stages. The arthrosporus stage, or the vegetative stage, has bright orange or reddish frutications. It is usually the first to appear and has smaller fruit bodies, which are reguarly hemispherical, dark reddish orange, and opaque due to the dense outer layer consisting largely of closely and irregularly packed arthrospores, or vegetative spores. These spores are formed from vegetative hyphal tissue, or the everyday tissue that comprises the fungus. This stage is quite firm but elastic, with a solid consistency.

The basidiferous stage, or reproductive stage, is bigger and more irregular and lobed, because the surface layer is thrown into a few relatively coarse convoluted folds and also because small group so neighboring fruit bodies coalesce and stick together. This reproductive stage appears to be pale yellow and semi-translucent due to the lack of the thick layer of arthrospores. It has instead basidiospores, which are formed on specialized reproductive structures called basidia that occur in the phylum Basidiomycota. This stage is gelatinous, not distinctly rooted, but attaches to the substrate by a central point.

The main difference biologically is that the basidiferous stage allows for sexual reproduction: the bi-nucleate cell (cell with two nuclei) undergoes karyogamy and the two nuclei fuse. Meiosis, or sexual recombination, occurs, and genetically different daughter cells result. In the vegetative stage, it’s as if the fungi puts a piece of itself in a spore. The resulting individual that grows from this spore should be genetically identical to the parent in most cases.

D. stillatus produces both stages simultaneously and close together so that often one observes what looks like two separate morphological species in close proximity. In both stages, when the spores depart the fungus and lands on a suitable substrate, both types of spores germinate and produce another specimen.

The basidia of D. stillatus are shaped like tuning forks. D. stillatus produces both catenate or chained arthrospores as well as spores that are oblong, curved cylindrical. The hyphae are septate, with divisions between different hyphal cells, and there are no clamp connections (a special type of cellular connection). It can be distinguished from most other species in Dacrymyces because it has an arthrosporus stage, though recently some other species (D. ellisii) have been defined with such a stage as well.

Specimens of D. stillatus have been found across Europe: Austria, Finland, France, Germany, Great Britain, Holland, Italy, Norway, Sweden, and Switzerland. They also are found in New Zealand, and along the western coast of the United States.

The family Dacrymycetaceae is widely distributed in temperate regions, mostly in the northern hemisphere. Individuals have been documented in Europe, Japan, and the Americas.

This saprotrophic, or decomposer, jelly fungus is notable for its small orange gelatinous appearance. Its common name is the Jelly Spot Fungus. Growing to sizes between 2-8mm, Dacrymyces stillatus is gregarious and appears in large groups and clusters on coniferous and deciduous woods. The fruiting bodies are broad, round, convex and at length plicate, meaning that it can grow to become shell or fan shaped.

It frequently grows on the stumps of trees, fallen branches and human construction. D. stillatus decays wood rails used in human homes, fences and railroads, particularly in Europe. This fungus consumes mostly the lignin in the wood, which is integral in the decomposition process, but structurally weakens wooden man-made structures. In many parts of the world where it appears, D. stillatus is considered a pest.

D. stillatus appears mainly during wetter periods, when it absorbs water, expands its size and grows. As a jelly fungus, D. stillatus can survive in desiccated form during drier periods. It dries as a rusty-brown crust on the substrate and can be revived with moisture. It is among the first fungi to appear after a rain, the dried, fruiting bodies quickly regaining their gelatinous texture.

There is some debate about the naming of D. stillatus versus D. deliquescens. Older literature reported the two as separate species, with D. stillatus distinguishable due to its bright orange color which is persistent. Furthermore, it is smaller, less depressed (maintains roundness) and firmer. However, Lorene L. Kennedy (1956) reports that D. stillatus is merely the bright orange arthrosporous or imperfect state of D. deliquescens, as opposed to the pale yellow basidiferous state. Now, D. stillatus is considered the preferred synonym to D. deliquescens and describes both states. Currently, this name is still widely accepted in the academic community.

Historically, people thought this this fungus was only found in coniferous forests. Later, scientists realized that they are found on both angiosperms and gymnosperms (coniferous and deciduous), consuming both soft and hard woods. In California, it has been found on the Monterey pine (Pinus radiata).

Away from the forest, this fungus is also a common occurrence on man made structures such as fence posts, decks, pine rails (for train tracks) and in houses. In Northern Europe, work has been done to prevent this fungus from speeding the decay of wood used in construction.

In terms of climate, it prefers wetter, temperate habitats. It will generally fruit all year whenever moisture is available.

It can be distinguished from two other common jelly fungi, D. palmatus and Tremella mesenterica by its smaller size and shape, appearing as individual spheres rather than in convoluted lobes.

Historically, Dacrymyces, along with other jelly fungi were considered part of the order Tremellales, but since then, the taxonomic classification has been reevaluated and the two separated. There are however many species of lobed yellow jelly fungi in order Tremellales.

Most jelly fungi are edible, but usually not palatable, often tasting like soil. Some species of the order Tremellales are used in Asian and Western cuisine. A notable one is Witch’s Butter (Tremella mesenterica). Typically, jelly fungi are dried and then reconstituted for consumption. A common culinary use for jelly fungus is in soups.

Due to its small size, however, D. stillatus in particular is not of culinary value. Its larger relative, the spongy D. palmatus is sometimes eaten.

This fungus has historically been studied for its bright orange hues, which are indicative of the carotenoids it contains. α-carotene, β-carotene, ξ-carotene, torulene, crypoxanthin, zeaxanthin, and phytofluene have been associated with with D. stillatus. The β-carotene occurs in significant quantities. β-carotene exists in many naturally orange organisms. This organic compound is the primary source of vitamin A.

Some species in the family Dacrymycetaceae are known to produces antibiotics, but these are not used commercially.