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Lichen: Porpidia hydrophila

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Porpidia hydrophila

Porpidia hydrophila

Porpidia hydrophila in situ

Porpidia hydrophila in situ

Name: Porpidia hydrophila (Fr.) Hertel & A.J.Schwab (1984)
Pronunciation: porpidia hydrophila
Conservation Evaluation: Least Concern
Body Type: Crustose
Description: A smooth surfaced creamy white to orange thallus with no distinct prothallus unless in contact with other crustose lichens (especially other Porpidia species) in which case dark or black lines form between them producing a mosaic of types. At times the smooth surface may have fine cracks, rarely large cracks (areolate). Pycnidia are abundant. Oxidation of the surface of the thallus produces the orange colour. Apothecia are common, black and reach sizes of 2.5mm. The discs are jet black but are frequently pruinose (dusting of white crystals). Discs are generally flat to convex; young specimens may be sub concave. It lacks isidia and soredia.
Chemical Tests: Medulla: C-, K-, Pd-. No lichen products detected.

Nature Notes: This is an upland acid rock species frequently found in amphibious conditions such as on rocks in streams or boggy moorland where they are washed by freshwater regularly. An oblique section through an apothecium shows a characteristic vivid blue-green colouration. This is a useful feature for distinguishing it from other Porpidia species.
Photographed:
in Co. Mayo near Erriff Bridge.
Similar species: Porpidia cinereoatra
Vice county distribution map: See map.
Link: Map this species on the Lichen Survey

Other species recorded in Ireland:

  • Porpidia cinereoatra (Ach.) Hertel & Knoph
  • Porpidia contraponenda (Arnold) Knoph & Hertel
  • Porpidia crustulata (Ach.) Hertel & Knoph
  • Porpidia flavicunda (Ach.) Gowan
  • Porpidia glaucophaea (Körb.) Hertel & Knoph
  • Porpidia macrocarpa (DC.) Hertel & A.J.Schwab
  • Porpidia melinodes (Körb.) Gowan & Ahti
  • Porpidia platycarpoides (Bagl.) Hertel
  • Porpidia soredizodes (Lamy ex Nyl.) J.R.Laundon
  • Porpidia speirea (Ach.) Kremp.
  • Porpidia tuberculosa (Sm.) Hertel & Knoph

Text and images © Paul Whelan, 2010.