Ochrolechia africana
in Tidewater, Virginia
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Pertusariales
Family: Ochrolechiaceae
Genus: Ochrolechia
Species:
O. africana
Binomial name
Ochrolechia africana
Vain. (1926)

Ochrolechia africana, commonly known as the frosty saucer lichen, is a species of crustose and corticolous (bark-dwelling) lichen in the family Ochrolechiaceae. It is a widely distributed species, found in tropical and subtropical areas of southern Africa, Asia, Australia, North America, and South America. The lichen is characterized by the presence of a white "frosty" or powdery apothecia.

Taxonomy

The lichen was scientifically described as a new species in 1926 by Finnish lichenologist Edvard August Vainio. The type specimen was collected by mycologist Paul Andries van der Bijl from South Africa, from "Durban Trunk of tree" in 1921. The specific epithet refers to the type locality.[1] A common name used in North America is "frosty saucer lichen".[2]

Description

Ochrolechia africana has a crustose, yellowish-grey to gray thallus with a surface texture ranging from smooth to warted (verruculose or verrucose).[3] The apothecia tend to be under 1.5 mm (0.1 in) in diameter, and have thick margins; they are often covered with a "frosty"-looking pruina, although there are forms that lack pruina.[2] The algal layer makes an almost complete layer under the hypothecium, forming abundant but discontinuous clumps.[4] The ascospores measure 43–67 by 18–30 μm.[2]

UV-illuminated thallus and apothecia of Ochrolechia africana; the yellowish colour results from the fluorescence of lichexanthone.

Ochrolechia africana contains several secondary chemicals: the orcinol depsides gyrophoric acid, lecanoric acid, 5-methyl-O-methylhiascic acid, 4,5-di-O-methylhiascic acid, and the xanthone lichexanthone. It is this latter compound that causes the lichen to fluoresce bright yellow when shone with a UV light.[4]

The Chinese alpine species Ochrolechia alticola is somewhat similar in appearance to O. africana, but differs in the C+ red reaction of the apothecial margin cortex, the absence of 5-O-methylhiascic acid, as well as its habitat.[5]

Habitat and distribution

Ochrolechia africana is a widely distributed species, found in tropical and subtropical areas of southern Africa, Asia, Australia,[6] North America, and South America. Reported as new to China in 2013, it is one of about 25 Ochrolechia species known to occur in that country. It typically grows on both the wood and bark of deciduous trees,[3] although it has also been recorded growing on rocks.

Irwin Brodo and James Lendemer reported on an atypical population of Ochrolechia africana they found in the Coastal Plain of southeastern North America; these lichens were sorediate and fertile, rather than the typical asorediate and fertile population that was expected.[7]

Parasites

Cornutispora lichenicola is a lichenicolous fungus that has been reported growing on Ochrolechia africana lichens in Bolivia.[8] In North America, the fungus Roselliniopsis tropica has been found on O. africana populations in the southeastern United States; infection by the fungus results in the formation of swollen gall-like structures on the lichen thalli.[9] In the Himachal Pradesh and Karnataka districts of India, a new species of lichenicolous fungus, Lichenodiplis ochrolechiae, was found infesting the thallus and apothecial discs of local O. africana populations.[10]

References

  1. ↑ Vainio, E.A. (1926). "Lichenes Africani Novi". Annales Universitatis Fennicae Aboënsis. A (in Latin). 2 (3): 1–33.
  2. 1 2 3 Brodo, Irwin M.; Sharnoff, Sylvia Duran; Sharnoff, Stephen (2001). Lichens of North America. Yale University Press. pp. 464–465. ISBN 978-0-300-08249-4.
  3. 1 2 Gao, Tong-Li; Ren, Qiang (2013). "New records of Ochrolechia and Placopsis from the Hengduan Mountains, China". Mycotaxon. 122 (1): 461–466. doi:10.5248/122.461.
  4. 1 2 Brodo, Irwin M. (1991). "Studies in the lichen genus Ochrolechia. 2. Corticolous species of North America". Canadian Journal of Botany. 69 (4): 733–772. doi:10.1139/b91-099.
  5. ↑ Ren, Qiang (2017). "A revision of the lichen genus Ochrolechia in China". The Lichenologist. 49 (1): 67–84. doi:10.1017/s0024282916000529. S2CID 89760884.
  6. ↑ "New Australian and Australian state lichen and lichenicolous lichen reports". Journal of the Hattori Botanical Laboratory (90): 269–291. 2001.
  7. ↑ Brodo, Irwin M.; Lendemer, James C. (2012). "On the perplexing variability of reproductive modes in the genus Ochrolechia: Notes on O. africana and O. arborea in eastern North America". Opuscula Philolichenum.
  8. ↑ Flakus, Adam; Kukwa, Martin (2012). "New records of lichenicolous fungi from Bolivia". Opuscula Philolichenum. 11: 36–48.
  9. ↑ Lendemer, James; Harris, Richard C. (2014). "Studies in Lichens and Lichenicolous Fungi No. 17 – Notes on Lichens from the Coastal Plain of Southeastern North America". Opuscula Philolichenum. 13: 8–19.
  10. ↑ Joshi, Yogesh; Falswal, Arti; Tripathi, Manish; Halda, Josef F. (2017). "Lichenodiplis ochrolechiae, a new species of lichenicolous fungi from India" (PDF). Sydowia. 69 (69): 19–22. doi:10.12905/0380.sydowia69-2017-0019.
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