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Lichen: Thelotrema lepadinum

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Barnacle-like apothecia

Barnacle-like apothecia

Thelotrema lepadinum

Thelotrema lepadinum

Vice County map of Thelotrema lepadinum

Name: Thelotrema lepadinum (Ach.) Ach. (1803)

Pronunciation: To be uploaded

Conservation Evaluation: Least Concern.

Body Type: Crustose

Description: The thallus varies from grey to white and may be smooth or rough.  The apothecia have volcano-like thalline (same colour as the thallus) rims. Inside these are smaller ‘proper’ rim margins around the disc. The discs are black and may be covered with white crystals giving them a grey pruinose appearance.

Chemical Tests: None. No lichen products have been found.

Nature Notes: This lichen has been referred to as bark barnacles. On rough bark it does indeed look like barnacles because of the rough thalline margins and wide openings. On smooth bark the apothecia are more conical and volcano-like with narrow openings. The species is sensitive to air pollution and is an indicator of ancient woodlands. It prefers areas that are shaded (canopy cover). It has been found on silica-rich rocks, but this is rare. Sometimes it is host to the lichenicolous fungus Skyttea nitschkei.

Looks Like: Thelotrema macrosporum or T. petractoides.

Vice county distribution map: See map

Link: Map this species on the Lichen Survey

Other species recorded in Ireland:

  • Thelotrema isidioides (Borrer) R.Sant.
  • Thelotrema macrosporum P.M.Jørg. & P.James
  • Thelotrema petractoides P.M.Jørg. & Brodo

Text and images © Paul Whelan, 2010.