Nidulariaceae

Nidulariaceae
Bird's nest fungi, Crucibulum laeve
Scientific classification
Kingdom:	Fungi
Subkingdom:	Dikarya
Phylum:	Basidiomycota
Subphylum:	Agaricomycotina
Class:	Agaricomycetes
Subclass:	Agaricomycetidae
Order:	Agaricales
Family:	Nidulariaceae Dumort. (1822)
Genera
Crucibulum Cyathus Mycocalia Nidula Nidularia

Nidulariaceae
Mycological characteristics
	glebal hymenium
	cap is infundibuliform
	hymenium attachment is not applicable
	lacks a stipe
	spore print is brown
	ecology is saprotrophic

The Nidulariaceae are a family of fungi in the order Nidulariales. Commonly known as the bird's nest fungi, their fruiting bodies resemble tiny egg-filled birds' nests. As they are saprobic, feeding on decomposing organic matter, they are often seen growing on decaying wood and in soils enriched with wood chips or bark mulch; they have a widespread distribution in most ecological regions. The five genera within the family, namely, Crucibulum, Cyathus, Mycocalia, Nidula, and Nidularia, are distinguished from each other by differences in morphology and peridiole structure; more recently, phylogenetic analysis and comparison of DNA sequences is guiding new decisions in the taxonomic organization of this family.

History

Bird's nest fungi were first mentioned by Flemish botanist Carolus Clusius in Rariorum plantarum historia (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 Traité des champignons (1790–3), proposed the erroneous notion that peridioles were ejected from the fruiting bodies by some sort of spring mechanism.^[1]

Description

The Nidulariaceae has a gasteroid fruiting body, meaning that the spores develop internally, in an angiocarp. Fruiting bodies are typically gregarious (growing together in groups, but not joined together). Young fruiting bodies are initially covered by a thin membrane that dehisces irregularly or by a circumscissile split, in a circular line around the circumference of the cup opening. Fruiting bodies (also called peridia) are small, generally between 5–15 mm wide and 4–8 mm high, urn- or vase-shaped, and contain one to several disc-shaped peridioles that resemble tiny eggs.^[2]

Peridiole structure

Peridioles contain glebal tissue, basidia, and basidiospores, surrounded by a hardened wall. They are commonly lenticular in shape (like a biconvex lens), measuring 1–3 mm in diameter. The color of the peridioles is characteristic of the genera: Cyathus has black peridioles, Nidularia and Nidula have brown preidioles, Mycocalia has yellow- to red-brown peridioles, and Crucibulum has black peridioles that are surrounded by a whitish membrame called the tunica, which makes them appear white.^[3] In most species, the peridioles are dispersed by rain, but they may also be free in the peridium, surrounded by a jelly-like mucilage.^[4]

Microscopic characteristics

Basidiospores are oval or elliptical in shape, smooth, hyaline, and thin-walled.^[2]

Habitat and distribution

Species in this family are cosmopolitan in distribution, and are largely saprobic, obtaining nutrition from the decomposition of wood and plant organic matter.

Life cycle

The life cycle of the Nidulariaceae, 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). Like other wood-decay fungi, this life cycle may be considered as two functionally different phases: the vegetative stage for the spread of mycelia, and the reproductive stage for the establishment of spore-producing structures, the fruiting bodies.^[5]

The vegetative stage encompasses those phases of the life cycle involved with the germination, spread, and survival of the mycelium. Spores germinate under suitable conditions of moisture and temperature, and grow into branching filaments called hyphae, pushing out like roots into the rotting wood. These hyphae are homokaryotic, containing a single nucleus in each compartment; they increase in length by adding cell-wall material to a growing tip. As these tips expand and spread to produce new growing points, a network called the mycelium develops. Mycelial growth occurs by mitosis and the synthesis of hyphal biomass. When two homokaryotic hyphae of different mating compatibility groups fuse with one another, they form a dikaryotic mycelia in a process called plasmogamy. Prerequisites for mycelial survival and colonization a substrate (like rotting wood) include suitable humidity and nutrient availability. The majority of Nidulariaceae species are saprobic, so mycelial growth in rotting wood is made possible by the secretion of enzymes that break down complex polysaccharides (such as cellulose and lignin) into simple sugars that can be used as nutrients.^[6]

After a period of time and under the appropriate environmental conditions, the dikaryotic mycelia may enter the reproductive stage of the life cycle. Fruiting body formation is influenced by external factors such as season (which affects temperature and air humidity), nutrients and light. As fruiting bodies develop they produce peridioles containing the basidia upon which new basidiospores are made. Young basidia contain a pair of haploid sexually compatible nuclei which fuse, and the resulting diploid fusion nucleus undergoes meiosis to produce basidiospores, each containing a single haploid nucleus.^[7] The dikaryotic mycelia from which the fruiting bodies are produced is long-lasting, and will continue to produce successive generations of fruiting bodies as long as the environmental conditions are favorable.

Spore dispersal

The nests are splash cups. When a raindrop hits one at the right angle, the walls are shaped such that the eggs are expelled a good distance from the nest. Some species have a sticky trailing thread, a funicular cord, attached to the peridiole. If that thread encounters a twig on its flight the egg will swing around and wrap itself around the twig. The spores can then germinate there and start the life cycle over again.

Genera

There are five genera in the Nidulariaceae family.

Crucibulum

Fruiting bodies light tan to cinnamon-colored, cup- or crucible-shaped, and typically 1.5–10 mm wide by 5–12 mm tall.

Cyathus

Fruiting bodies vase-, trumpet- or urn-shaped with dimensions of 4–8 mm wide by 7–18 mm tall. Fruiting bodies are brown to gray-brown in color, and covered with small hair-like structures on the outer surface. Complex funicular cord.

Mycocalia

Small barrel- to lens-shaped fruiting bodies, usually 0.5–2 mm broad, that grow singly or in small groups.

Nidula

Fruiting bodies between 3–8 mm in diameter, 5–15 mm tall, and cup- or urn-shaped—having almost vertical sides with the lip flared outwards; color ranging from white, grey, buff, or tawny.

Nidularia

Typically 0.5–6 mm in diameter x 0.5–3 mm tall. They may be somewhat irregular in shape, or have a well-formed cup that is thin and fragile. No funicular cord.

Phylogenetics

The Nidulariaceae were formerly classified in the class Gasteromycetes, but this class has been shown to be polyphyletic, and an artificial assemblage of unrelated taxa that have independently evolved a gasteroid body type. A 2002 phylogenetic study of ribosomal DNA from various gasteriod species, including Cyathus striatus and Crucibulum laeve as representatives of the Nidulariaceae, were shown to belong to the euagarics clade, a monophyletic grouping of species from various genera: Hymenogaster, Hebeloma, Pholiota, Psathyrellus, Agaricus campestris, Amanita, and Tulostoma.^[8] The euagarics are mostly gilled mushrooms, but they do include two gasteroid lineages, including a puffball lineage in the Lycoperdales, and the bird's nest fungi in the Nidulariales.^[9]

Further reading

• Mushrooms of Northeastern North America (1997) ISBN 0-8156-0388-6
• Alexopolous, C.J., Charles W. Mims, M. Blackwell et al., Introductory Mycology, 4th ed. (John Wiley and Sons, Hoboken NJ, 2004) ISBN 0-471-52229-5
• Arora, David. (1986). "Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi". 2nd ed. Ten Speed Press. ISBN 0898151694

Footnotes

1. ^ Brodie p. 15.
2. ^ ^{a b} Miller HR, Miller OK. (1988). Gasteromycetes: morphological and developmental features, with keys to the orders, families, and genera. Eureka, Calif: Mad River Press. ISBN 0-916422-74-7. 
3. ^ Lloyd CG. (1906). "The Nidulariaceae". Mycological Writings 2: 1–30. 
4. ^ Cannon PF, Kirk PM. (2007). Fungal Families of the World. Wallingford: CABI. ISBN 0-85199-827-5. 
5. ^ Schmidt O. (2006). Wood and Tree Fungi: Biology, Damage, Protection, and Use. Berlin: Springer. pp. 10–11. ISBN 3-540-32138-1. 
6. ^ Deacon pp. 231–34.
7. ^ Deacon pp. 31–32.
8. ^ Binder M, Bresinsky A.; Bresinsky, Andreas (2002). "Derivation of a polymorphic lineage of Gasteromycetes from Boletoid ancestors". Mycologia 94 (1): 85–98. doi:10.2307/3761848. JSTOR 3761848. 
9. ^ Hibbett DS, Pine EM, Langer E, Langer G, Donoghue MJ. (1997). "Evolution of gilled mushrooms and puffballs inferred from ribosomal DNA sequences". Proceedings of the National Academy of Sciences U.S.A. 94 (22): 12002–6. doi:10.1073/pnas.94.22.12002. PMC 23683. PMID 9342352. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=9342352. Retrieved 2009-04-11. 

References

• Alexopoulos CJ, Mims CW, Blackwell M. (1996). Introductory Mycology. New York: Wiley. ISBN 0-471-52229-5. 
• Brodie HJ. (1975). The Bird's Nest Fungi. Toronto: University of Toronto Press. ISBN 0-8020-5307-6. 
• Deacon J. (2005). Fungal Biology. Cambridge, MA: Blackwell Publishers. ISBN 1-4051-3066-0. 

External links

• MushroomExpert.com Nidulariaceae