Observation 103481: Pertusaria melanochlora (DC.) Nyl.
When: 2012-07-28
Who: zaca
No herbarium specimen

Notes: This is just one of the several specimens that I observed at this location of another species unknown to me.
The first question I put to myself while seeing this specimen was: the cream round things are soralia or apothecia?
In the field I could not decide. [For the purpose of comparing see, for instance, the soralia of Pertusaria albescens in image 213047]. Only magnifying the photos I conclude that must be apothecia. The chemistry gave C-, K-, KC-. The microscopy showed very big spores, some with more than 225 × 85 µm, and 1 spore/ascus.
Confronting with the list of Pertusaria spp. in the checklist of this location (See the Notes of the location), the following species are therein:

Pertusaria albescens (HUDS.) M. CHOISY & WERNER: W, 27502Qc.
Pertusaria amara (ACH.) NYL.: W, 27509s; E, 27665Qc; (S-H).
Pertusaria excludens NYL.: W, 27606s; (S-H).
Pertusaria ficorum ZAHLBR.: E, on O/ea europaea (MB).
Pertusaria hemisphaerica (FLÖRKE) ERICHSEN: E, on Pinus (MB).
Pertusaria heterochroa (MÜLL. ARG.) ERICHSEN: E, 27646 on dead trunk of Aeonium arboretum.
Pertusaria melanochlora (DC.) NYL.: W, 27487s.
Pertusaria pluripuncta NYL.: E, 35285s.
Pertusaria pseudocorallina (LlLJ.) ARNOLD: E, on exposed vertical outcrop (ac).
Pertusaria pustulata (ACH.) DUBY: W, 27547Qc.
Pertusaria velata (TURNER) NYL.: E, 27632Qc, 27OO7Qc

From these only four live on rock: P. excludens, P. melanochlora, P. pluripuncta and P. pseudocorallina.
The first one is sterile, the fourth is much different and also usually sterile, the third has yellowish thallus and much smaller spores. So, only P. melanochlora is left.

To achive this one in the Identification key to Pertusaria in Europe and the Mediterranean one has the following evolution on the key:

[1a] On rock; [2a] Thallus, when fully developed, with apothecia; [3b] Ascospores persistently colourless;
[8b] Apothecia persistently perithecium-like, with punctiform discs (ostioles), one or several in each fertile wart;
[47b] Fertile warts sharply delimited; [55c] Thallus K-; [81a] Thallus C-; [82a] On rock; [83b] Thallus papillate-isidiate;
[84a] Medulla KC+ violet, with bitter taste; thallus grey, densely covered by simple to branched, to about 5 mm high, 0.5-1 mm thick papillae; fertile warts stalked like papillae, finally irregularly nodular, to about 3.5 mm wide, with usually several, finally widened ostioles confluent in a disc; ascospores 1/ascus, about 180-300 × 70-100 µm; medulla and ostioles P+ red, KC+ violet; picrolichenic and protocetraric acids; SW Europe, Wales, W Norway; probably heterogeneous
—→ P. melanochlora (DC.) Nyl.

Only the last choice made me doubt, since I performed the KC test on the medulla (cutting the base of a stalked ostiole) and the reaction was not KC+ violet, being either negative or something indefinite. However, I see no alternative, since the other choice in the key, leads to a sterile species (P. schaereri).
The reddish P+ reaction was observed on an apothecium under the microscope.
I found only one photo of a specimen classified as P. melanochlora similar to mine: see dbiodbs.


Chemical reactions;
Chemical reactions (cont)- P reaction
Microscopy I;
Microscopy II.

Proposed Names

29% (1)
Eye3 Eyes3
Used references: See the Notes
Based on microscopic features
Based on chemical features

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Not very productive, as you could see!
By: zaca
2012-07-31 15:20:05 PDT (-0700)
Wow, that’s an impressive analysis!
By: Jason Hollinger (jason)
2012-07-31 15:10:37 PDT (-0700)

Created: 2012-07-31 13:51:31 PDT (-0700)
Last modified: 2012-07-31 15:19:32 PDT (-0700)
Viewed: 171 times, last viewed: 2017-06-20 07:28:27 PDT (-0700)
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