Placynthium subradiatum (Nyl.) Arnold

Image location: Planalto das Cezaredas, Portugal

It took me more or less two and a half years to “rediscover” these specimens (observatiion 177032), after some failed past attempts. This is a very distinctive and uncommon species of Placynthium, growing on calcareous rock. The common species here in this genus is P. nigrum, that I also found this day at the same habitat (see observation 272274). The grow form of P. subradiatum, which I think to be the species under consideration, fits quite well in these specimens judging by the photos available at the internet, namely the following: http://lichenportal.org/... http://www.irishlichens.ie/pages-lichen/l-235.html http://dryades.univ.trieste.it/... http://www.waysofenlichenment.net/... It can be characterized as follows (excert from Irish lichens): “Blackish or dark olive-brown thallus forming more or less complete rosettes, narrow rings or arcs, dying from the centre. Margin with tightly packed, adpressed lobes, prothallus inconspicuous” . It is said to be rarely fertile and so I was lucky to saw a big amount of apothecia, which are really tiny. I have already looked to the collected sample, which to the naked eye seems like dust, and my next problem will be to select some apothecia from it, since I can’t see any differentiation between apohecia and the other pieces of the thallus that came as a result of scratching the thallus with a knife. A description of P. subradiatum can be found at http://lichenportal.org/portal/taxa/index.php?taxon=56010.

For more information about this, see the observation page at Mushroom Observer. English | español | français | italiano | македонски | മലയാളം | português | +/−