Terana caerulea (or Terana coerulea), commonly known as the cobalt crust fungus or velvet blue spread, is a saprobic crust fungus in the family Phanerochaetaceae. Usually found in warm, damp hardwood forests on the undersides of fallen logs and branches of deciduous trees, this unique fungus has been described as "blue velvet on a stick". This species was chosen as fungus of the year for 2009 by the German Mycological Society.
Terana caerulea is resupinate, meaning the fruiting body lies on the surface of the substrate, with the hymenium exposed to the outside. The fruiting body is 2–6 mm thick. It is dark blue with a paler margin, with a velvety or waxy texture when moist, but crusty and brittle when dry. The fruiting body is firmly attached to its growing surface except at the edges. In nature, the fungus surface is typically found pointing downward, which helps facilitate spore dispersal. It usually grows on dead deciduous wood, often ash and hazel. The spore print is white. Spores are ellipsoidal, smooth, thin-walled, hyaline or pale blue, with dimensions of 7–12 by 4–7 µm. The four-spored basidia are club-shaped, hyaline or blue, with dimensions of 40–60 by 5–7 µm.
The cobalt crust has a worldwide distribution in warmer climates, and has been reported from Asia, Africa, New Zealand, North America, the Canary Islands, Europe, Taiwan, Thailand, and Turkey.
When activated by external treatments such as high temperature (42 °C (108 °F)), exposure to vapors of toxic solvents, or contact with a water-toluene mixture, T. caerulea produces an antibiotic named cortalcerone (2-hydroxy-6H-3-pyrone-2-carboxaldehyde hydrate), that inhibits the growth of Streptococcus pyogenes. The metabolic biosynthesis of this compound starting from the initial precursor glucose has also been studied.
Compounds with so-called "benzobisbenzofuranoid" skeletons have been isolated and identified from T. caerulea, namely, corticins A, B, and C.
This species, which for a member of the corticioid fungi is relatively easy to identify, was first described in 1779 by Jean-Baptiste Lamarck, who is best known for proposing an early theory of evolution. Lamarck used the name Byssus caerulea, and various other designations were subsequently employed, until in 1828 Fries classified it as Thelephora violascens variety coerulea. According to rule 13.1.d. of the International Code of Botanical Nomenclature, valid publication of fungal names is treated as beginning with Fries's publication of "Systema Mycologicum" in 1821 and following years. This means that the correct species name is coerulea, not caerulea. Both names are found frequently in the literature. Strangely enough, Lamarck's name Byssus has now come to be applied to a plant genus - a fundamentally different organism.
In 1763 Michel Adanson had devised the genus name Terana for similar crust fungi and in 1891 Otto Kuntze included coerulea in that genus to create the modern name. Apart from this, the genus Pulcherricium was proposed by Parmasto in 1968 for this one species and the name Pulcherricium caerulea/coerulea is sometimes seen, but the designation Terana is better established.
- "Phlebia coccineofulva, Hyphoderma puberum, and Pulcherricium caeruleum — some patriotic corticioid (crust) fungi Tom Volk's Fungus of the Month for July 2000". Retrieved 2009-02-09.
- "Pilz des Jahres 2009: Blauer Rindenpilz (Pulcherricium caeruleum (Lam.) Kuntze 1891)". Deutsche Gesellschaft für Mykologie (German Mycological Society). Retrieved 2017-09-13.
- Miller HR, Miller OK (2006). North American Mushrooms: a Field Guide to Edible and Inedible Fungi. Guilford, Conn: Falcon Guide. p. 433. ISBN 978-0-7627-3109-1. Google Books
- "sita.siv-ars.it" (PDF). Retrieved 2009-02-09.[dead link]
- Ellis, J. B.; Ellis, Martin B. (1990). Fungi Without Gills (Hymenomycetes and Gasteromycetes): an Identification Handbook. London: Chapman and Hall. p. 165. ISBN 978-0-412-36970-4.
- "wood-rotting fungi". Archived from the original on 2012-12-12. Retrieved 2009-02-09.
- Krieglsteiner GJ. (1983). "The blue corticium Pulcherricium caeruleum and its occurrence in Europe". Zeitschrift für Mykologie 49(1): 61–72.
- Wu S-H, Chen Z-C. (1989). "Pulcherricium caeruleum new record (Fr. Parm. Corticiaceae, Basidiomycetes). A new record from Taiwan". Taiwania 34(1): 1–4.
- Hjorstam K, Ryvarden L. (2008). "Aphylophorales from Northern Thailand". Nordic Journal of Botany 2(3): 273–281.
- Sesli E. (2008). "Checklist of the Turkish ascomycota and basidiomycota collected from the Black Sea region". Mycotaxon 99: 71–74. PDF
- Neveu A, Baute R, Bourgeois G, Deffieux G. (1974)."Recherches sur le pigment bleu du champignon Corticium caeruleum (Schrad. ex Fr.) Fr. (Aphyllophorales)". Bulletin de la Societe de pharmacie de Bordeaux 113(3): 77–85.
- Baute R, Baute M-A, Deffieux G, Filleau M-J. (1976). "Cortalcerone, a new antibiotic induced by external agents in Corticium caeruleum". Phytochemistry 15(11): 1753–1755.
- Baute R, Baute M-A, Deffieux G, Filleau M-J. (1977). "Conversion of glucose to cortalcerone via glucosone by Corticium caeruleum". Phytochemistry 16(12): 1895–1897.
- Baute M-A, Baute R. (1984). Occurrence among macrofungi of the bioconversion of glucosone to cortalcerone. Phytochemistry 23(2): 271–274.
- Baute R, Baute M-A, Deffieux G. (1987). Proposed pathway to the pyrones cortalcerone and microthecin in fungi". Phytochemistry 26(5): 1395–1397.
- Briggs LH, Cambie RC, Dean IC, Hodges R, Ingram WB, Rutledge PS. (1976). "Chemistry of fungi. XI. Corticins A, B, and C, benzobisbenzofurans from Corticium caeruleum". Australian Journal of Chemistry 29: 179–190. Abstract
- Jean Baptiste Lamarck (1778). Flore Françoise ou Description succincte de toutes les plantes qui croissent naturellement en France (in French). 1. Paris: l'Imprimerie Royale. p. (103) in section "Méthode Analitique".
- See the Species Fungorum entry for Terana coerulea at .
- See editorial comment for Byssus coerulea at .
- See Encyclopedia Of Life entry at .