Dendrocollybia

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Dendrocollybia
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Tricholomataceae
Genus: Dendrocollybia
R.H.Petersen
& Redhead (2001)
Species:
D. racemosa
Binomial name
Dendrocollybia racemosa
(
Pers.
) R.H.Petersen & Redhead (2001)
Synonyms[3]
  • Agaricus racemosus Pers.
  • Collybia racemosa (Pers.) Quél.
  • Microcollybia racemosa (Pers.) Lennox[1]
  • Mycena racemosa (Pers.) Gray[2]

Dendrocollybia is a fungal

Lactarius and Russula—although the host
mushrooms may be decayed to the point of being difficult to recognize.

Dendrocollybia racemosa fruit bodies have small pale grayish-white or grayish-brown caps up to 1 cm (0.4 in) wide, and thin stems up to 6 cm (2.4 in) long. The species is characterized by its unusual stem, which is covered with short lateral branches. The branches often produce spherical slimeheads of translucent conidiophores on their swollen tips. The conidiophores produce conidia (asexual spores) by mitosis. Because the fungus can rely on either sexual or asexual modes of reproduction, fruit bodies sometimes have reduced or even missing caps. The unusual stems originate from black pea-sized structures called sclerotia. The anamorphic form of the fungus, known as Tilachlidiopsis racemosa, is missing the sexual stage of its life cycle. It can reproduce at relatively low temperatures, an adaptation believed to improve its ability to grow quickly and fruit on decomposing mushrooms.

Taxonomy and phylogeny

Phylogeny and relationships of D. racemosa and closely related fungi based on ribosomal DNA sequences[4]

The genus Dendrocollybia was first described in 2001, to accommodate the species previously known as Collybia racemosa. Before then, the so-named

synonyms.[3]

monophyletic group within a larger Lyophyllum–Tricholoma–Collybia clade that includes several species of Lyophyllum, Tricholoma, Lepista, Hypsizygus and the species C. racemosa. Hughes and colleagues could not identify a clade that included all four species of Collybia. Restriction fragment length polymorphism analysis of the ribosomal DNA from the four species corroborated the results obtained from phylogenetic analysis. Based on these results, as well as differences in characteristics such as the presence of unique stem projections, fruit body pigmentation, and macrochemical reactions
, they circumscribed the new genus Dendrocollybia to contain

Dendrocollybia
View the Mycomorphbox template that generates the following list
Gills on hymenium
Cap is conical or convex
saprotrophic
Edibility is unknown

C. racemosa.[4]

The fungus is

specific epithet racemosa is from the Latin word racemus—"a cluster of grapes".[12]

Description

From Esenbeck's Das System der Pilze und Schwämme (1816)

The

gills initially; as the fruit body matures the edge may roll out somewhat, but it also tends to fray or split with age. There may be shallow grooves on the cap that corresponds to the position of the gills underneath, which may give the cap edge a crenate (scalloped) appearance. The flesh is very thin (less than 1 mm thick)[13] and fragile, lacking in color, and has no distinctive odor or taste.[14] The gills are relatively broad, narrowly attached to the stem (adnexed), spaced closely together, and colored gray to grayish-tan, somewhat darker than the cap.[15] There are additional gills, called lamellulae, that do not extend all the way to the stem; they are interspersed between the gills and arranged in up to three series (tiers) of equal length.[13] Occasionally, the fungus produces stems with aborted caps, or with the caps missing entirely.[10]

Stem resembles the raceme of the currant-bush, from whence the berries have been plucked; branches terminated by hyaline beads which disappear.

— S.F. Gray, [2]

The stem is 4 to 6 cm (1.6 to 2.4 in) long by 1 mm thick, roughly equal in width throughout, and tapers to a long "root" which terminates in a dull black, roughly spherical sclerotium.[14] The stem may be buried deeply in its substrate.[13] The stem surface is roughly the same color as the cap, with a fine whitish powder on the upper surface. In the lower portion, the stem is brownish, and has fine grooves that run lengthwise up and down the surface.[15] The lower half is covered with irregularly arranged short branch-like protuberances at right angles to the stem that measures 2–3 by 0.5 mm. These projections are cylindrical and tapering, with ends that are covered with a slime head of conidia (fungal spores produced asexually). D. racemosa is the only mushroom species known that form conidia on side branches of the stem.[16] The sclerotium from which the stem arises is watery grayish and homogeneous in cross section (not divided into internal chambers), with a thin dull black outer coat, and measures 3 to 6 mm (0.12 to 0.24 in) in diameter.[14] American mycologist Alexander H. Smith cautioned that novice collectors will typically miss the sclerotium the first time they find the species.[17] The edibility of D. racemosa is unknown,[17] but as David Arora says, the fruit bodies are "much too puny and rare to be of value."[10]

Microscopic characteristics

The

conidia are 8.5–12 by 4–5 μm, peanut-shaped, non-amyloid (not changing color when stained with Melzer's reagent), clamped, and produced by fragmentation of the coarse mycelium.[1] Clamp connections are present in the hyphae.[17] Asexual spores are 10.0–15.5 by 3–4 μm, ellipsoid to oblong, non-amyloid, and contain granular contents.[13] The grayish color of the fruit bodies is caused by encrusted pigments (crystalline aggregates of pigment molecules, possibly melanin) that occur throughout the tissue of the stem and cap, including the gills; these pigments are absent in Collybia species.[4]

The lateral projections of the stem form conidia.

Similar species

In contrast to the three species of Collybia,[4] D. racemosa shows negligible reactivity to common chemical tests used in mushroom identification, including aniline, alpha-napthol, guaiacol, sulfoformol, phenol, and phenol-aniline.[1]

The cortex (outer tissue layer) of the sclerotium can be used as a diagnostic character to distinguish between D. racemosa and small white specimens of Collybia. The hyphae of the cortex of D. racemosa are "markedly angular", in comparison with C. cookei (rounded hyphae) and C. tuberosa (elongated hyphae).[18] The cortical layer in D. racemosa has an arrangement that is known as textura epidermoidea—with the hyphae arranged like a jigsaw puzzle. Heavy deposits of dark reddish-brown pigment are evident throughout the cortical tissue in or on the walls and the tips of hyphae.[4] The remaining Collybia species, C. cirrhata, does not form sclerotia.[18]

Anamorph form

The anamorphic or

mycelium to grow quickly and enhance its chances of fruiting on agaric mushrooms, which are generally short-lived.[21]

Habitat, distribution, and ecology

Russula crassotunicata has been verified as a host for Dendrocollybia.

Dendrocollybia racemosa is a

temperate regions of the Northern Hemisphere,[24][25] but rarely collected "probably due to its small size, camouflage color, and tendency to be immersed in its substrate."[1] In North America, where the distribution is restricted to the Pacific Northwest,[26] fruit bodies are found in the late summer to autumn, often after a heavy fruiting period for other mushrooms is over.[17] In Europe, it is known from the United Kingdom, Scandinavia,[27] and Belgium.[4] Dendrocollybia racemosa is in the Danish,[28] Norwegian,[29] and British Red Lists.[30]

The saprobic behaviors of Collybia and Dendrocollybia are slightly different. In the autumn, fruit bodies of C. cirrhata, C. cookei and C. tuberosa, can be found on blackened, leathery, mummified fruit bodies of their hosts. Sometimes, these species appear to be growing in the soil (or from their sclerotium in soil or moss), but usually not in huge clusters. In these cases it is assumed that the hosts are remnants of fruit bodies from a previous season. In all observed cases of D. racemosa, however, the hosts have not been readily observed, suggesting that rapid digestion of the host (rather than mummification) may have taken place. Hughes and colleagues suggest that this may indicate the presence of a different enzymatic system, and a differing ability to compete with other fungi or bacteria.[4]

See also

References

  1. ^ a b c d Lennox JW. (1979). "Collybioid genera in the Pacific Northwest". Mycotaxon. 9 (1): 117–231. Archived from the original on 2008-07-23. Retrieved 2010-05-13.
  2. ^ a b c d Gray SF. (1821). A Natural Arrangement of British Plants. London, UK: Baldwin, Cradock, and Joy. p. 620.
  3. ^ a b "Dendrocollybia racemosa (Pers.) R.H. Petersen & Redhead 2001". MycoBank. International Mycological Association. Retrieved 2012-07-05.
  4. ^
    doi:10.1017/S0953756200003415
    .
  5. ^ Antonín V, Halling RE, Noordeloos ME (1997). "Generic concepts within the groups of Marasmius and Collybia sensu lato". Mycotaxon. 63: 359–68. Archived from the original on 2015-09-23. Retrieved 2010-05-13.
  6. ^ Persoon CH. (1794). "Dispositio methodica fungorum" [Methodical arrangement of the fungi]. Neues Magazin für die Botanik, Römer (in Latin). 1: 81–128.
  7. ^ Fries EM. (1821). Systema Mycologicum (in Latin). Vol. 1. Lundin, Sweden: Ex Officina Berlingiana. p. 134.
  8. ^ Quélet L. (1873). "Les champignons du Jura et des Vosges. IIe Partie" [Mushrooms of the Jura and the Vosges. 2nd Part]. Mémoires de la Société d'Émulation de Montbéliard (in French). 5: 333–427.
  9. ISBN 978-3-87429-254-2
    .
  10. ^
    ISBN 978-0-89815-169-5
    .
  11. ^ "Recommended English Names for Fungi in the UK" (PDF). British Mycological Society. Archived from the original (PDF) on 2011-07-16.
  12. ISBN 978-1-930513-49-5
    .
  13. ^ a b c d Wood M, Stevens F. "Collybia racemosa". California Fungi. Retrieved 2012-07-05.
  14. ^
    JSTOR 2481096
    .
  15. ^
    ISBN 978-90-5410-616-6
    .
  16. ^ Castellano MA, Cazares E, Fondrick B, Dreisbach T (2003). Handbook to additional fungal species of special concern in the Northwest Forest Plan (Gen. Tech Rep. PNW-GTR-572) (PDF) (Report). Portland, Oregon: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. pp. S3–S51.
  17. ^
    ISBN 978-0-472-85599-5
    .
  18. ^ a b Komorovska H. (2000). "A new diagnostic character for the genus Collybia (Agaricales)". Mycotaxon. 75: 343–6.
  19. JSTOR 3753686
    .
  20. ^ Watling R, Kendrick B (1977). "Dimorphism in Collybia racemosa". Michigan Botanist. 16 (2): 65–72.
  21. doi:10.1139/b91-002
    .
  22. doi:10.2509/pnwf.2006.001.009. Open access icon
  23. ISBN 978-0-12-509551-8
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  24. ISBN 978-0-85199-826-8
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  25. ISBN 978-90-5410-617-3
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  26. ^ Kuo M. (March 2005). "Dendrocollybia racemosa". MushroomExpert.Com. Retrieved 2010-05-12.
  27. ^ Oregon Biodiversity Information Center (2010). Rare, Threatened and Endangered Species of Oregon (PDF) (Report). Portland, Oregon: Institute for Natural Resources, Portland State University. p. 91. Archived from the original (PDF) on 2011-01-28.
  28. ^ Heilmann-Clausen J. "NERI – The Danish Red Data Book – Dendrocollybia racemosa (Pers.) R.H. Petersen & Redhead". National Environmental Research Institute, Denmark. Archived from the original on 2011-07-18. Retrieved 2010-05-12.
  29. ^ "Red List of Threatened Fungi in Norway". Norsk Rødliste 2006. The Herbarium, The Natural History Museums and Botanical Garden, University of Oslo. Retrieved 2010-10-26.
  30. ^ Evans S. (2009). The Red Data List of Threatened British Fungi (PDF) (Report). British Mycological Society.
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