Cyathus (crustacean)

''Cyathus'' is a genus of fungi in the Nidulariaceae, which is a family collectively known as the bird's nest fungi. They are given this name as they resemble tiny bird's nests filled with "eggs"structures large enough to have been mistaken in the past for seeds. However, these are now known to be reproductive structures containing spores. The "eggs", or ''peridioles'', are firmly attached to the inner surface of this fruit body by an elastic cord of mycelia known as a funiculus. The 45 species are widely distributed throughout the world and some are found in most countries, although a few exist in only one or two locales. ''Cyathus stercoreus'' is considered endangered in a number of European countries. Some species of ''Cyathus'' are also known as splash cups, which refers to the fact that falling raindrops can knock the peridioles out of the open-cup fruit body. The internal and external surfaces of this cup may be ridged longitudinally (referred to as plicate or striate); this is one example of a taxonomic characteristic that has traditionally served to distinguish between species.

Generally considered inedible, ''Cyathus'' species are saprobic, since they obtain nutrients from decomposing organic matter. They usually grow on decaying wood or woody debris, on cow and horse dung, or directly on humus-rich soil. The life cycle of this genus allows it to reproduce both sexually, with meiosis, and asexually via spores. Several ''Cyathus'' species produce bioactive compounds, some with medicinal properties, and several lignin-degrading enzymes from the genus may be useful in bioremediation and agriculture. Phylogenetic analysis is providing new insights into the evolutionary relationships between the various species in ''Cyathus'', and has cast doubt on the validity of the older classification systems that are based on traditional taxonomic characteristics.

Taxonomy

History

Bird's nest fungi were first mentioned by Flemish botanist Carolus Clusius in (1601). Over the next couple of centuries, these fungi were the subject of some controversy regarding whether the peridioles were seeds, and the mechanism by which they were dispersed in nature. For example, the French botanist Jean-Jacques Paulet, in his work (1790–1793), proposed the erroneous notion that peridioles were ejected from the fruit bodies by some sort of spring mechanism.Brodie (1975), p. 15. The genus was established in 1768 by the Swiss scientist Albrecht von Haller; the generic name is Latin, but it was originally derived from the Ancient Greek word , meaning 'cup'. The structure and biology of the genus ''Cyathus'' was better known by the mid-19th century, starting with the appearance in 1842 of a paper by Carl Johann Friedrich Schmitz, and two years later, a monograph by the brothers Louis René and Charles Tulasne. The work of the Tulasnes was thorough and accurate, and was highly regarded by later researchers. Subsequently, monographs were written in 1902 by Violet S. White (on American species), Curtis Gates Lloyd in 1906, Gordon Herriot Cunningham in 1924 (on New Zealand species), and Harold J. Brodie in 1975.

Infrageneric classification

The genus ''Cyathus'' was first subdivided into two infrageneric groups (i.e., grouping species below the rank of genus) by the Tulasne brothers; the "eucyathus" group had fruit bodies with inner surfaces folded into pleats (plications), while the "olla" group lacked plications. Later (1906), Lloyd published a different concept of infrageneric grouping in ''Cyathus'', describing five groups, two in the eucyathus group and five in the olla group.

In the 1970s, Brodie, in his monograph on bird's nest fungi, separated the genus ''Cyathus'' into seven related groups based on a number of taxonomic characteristics, including the presence or absence of plications, the structure of the peridioles, the color of the fruit bodies, and the nature of the hairs on the outer peridium:

*''Olla'' group: Species with a tomentum