Notes: This observation together with observation 165506 and observation 165507 are devoted to a group of crustose lichens growing on a branch of a shrub. This is my first attempt to consider a set of lichens growing together for the purpose of classification. I attached several photos of this group and include one with numbers to distinguish between them (4th photo). They have all different features and at first sight one can immediately say that:
I – Is a Graphidaceae, probably a Graphis or Phaeographis, the latter being more probable, due to the form of apothecia with open discs;
II – Resembles very clearly an Arthonia sp.. Which one? Only microscopy can help.
III – Is somewhat related in appearance to the genus Buellia, if one can confirm that the fruitbodies are apothecia, which is not clear due to their reduced dimensions.
Only the lichen marked as I is considered in this observation. The microscopy confirmed that it may belong to Phaeographis, the ascospores being pale brown coloured and even dark brown when over-mature.
According to the Ref. 1 (British Flora) and to Ref. 2 there are four species of this genus in europe.The existence of more than 5 transverse septa in the ascospores leads to one of two species: P. dendritica and P. smithii. Since the exciple is closed at the base, the match is P. dendritica. The following average values were obtained for the ascospores : Me = 34.7 × 7 um ; Qe = 4.9 (N=18), which are in the ranges given in Ref. 1.
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Created: 2014-05-11 17:19:52 CDT (-0500)
Last modified: 2014-05-11 18:02:20 CDT (-0500)
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