Observation 164727: Schadonia fecunda (Th. Fr.) Vězda & Poelt

When: 2014-05-03

Collection location: Planalto das Cezaredas, Portugal [Click for map]

Who: zaca

No specimen available

If my identification is correct this is another of our rare lichens. Let me start these notes giving some of its macro features:
- Growing on a piece of compactified soil (it looks like rock but disintegrates when touched) in a fence, sharing the space with another interesting lichen:
- The thallus is grey, pruinose, and well delimitated by a yellow-brown prothallus-like zone;
- Apothecia dark colored (black), up to 1.2 mm in diameter, licedeine, adnate, hollow inside.
With these features it could belong to many genera. However, the micro features permit to go further in the identification. Here are some:
- Hymenium with ~180 um high; Hypothecium red-brown: Epithecium dark-colored with some blue-green tinge;
- Paraphyses branched and anastomosing, seeming conglutinate;
- Asci saccate with 8 spores each;
- Spores muriform, with many cells, hialine when young and becoming light colored at maturity, for which I obtained the following average measures: Me = 29.3 × 12.9 um ; Qe = 2.3 (N=32).
Using the key in the British Flora (Reference 1 below) devoted to
Crustose Lichens: apothecia rounded; photobiont chlorococoid; ascospores colourless, septate (key 6c)
I came to the name Schadonia fecunda. It concerns a rare lichen in the Bristish Islands. However the dimensions of the spores given there ((30-)40-50(-60)) are a bit different from my specimen. Then I looked in the internet for more information and first found a page reporting the existence of that species in Finland. Next I found Reference 2, which is available in Google books. There I could saw that there exist two species (with descriptions) with an ARTIC? distribution: S. alpina (Greeland, Scandinavia, Siberia, and USA) and S. fecunda (Greenland, European Alps and British Columbia in N. A.). For both species the dimensions of the spores are similar to those of my specimen: 22-41 × 9-15 um for S. alpina and 22-40 × 10-18 um for S. fecunda. The main difference between them is the number of spores per ascum: 2-4 for S. alpina and 8 for S. fecunda. So, maybe the specimens collected in the British Islands have distinct spores dimension than the collected elsewhere.
Therefore, I believe that my specimen belongs to the species S. fecunda and not even the fact that I´m so far from the known existing places (almost 20 years ago) makes me doubt (I quote from Ref. 2: “It probably occurs more widely but is very inconspicuous” and note that this species is in the checklist of Spain, our neighbour country).


Microscopy: Apothecial section;
Microscopy: Apothecial section-Close up 1;
Microscopy: Apothecial section-Close up 2;
Microscopy: Paraphyses;
Microscopy: Asci 1;
Microscopy: Asci 2;
Microscopy: Spores.

Proposed Names

87% (1)
Eye3 Eyes3
Used references: Ref. 1 (British Flora): Smith et al. (Editors), The Lichens of Great Britain and Ireland, British Lichen Society, 2nd edition, 2009; Ref. 2: John W. Thomson, American Arctic Lichens, Volume II: The Microlichens, University of Wisconsin Press, 1996.
Based on microscopic features

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
The photos posted …
By: zaca
2014-05-07 04:51:07 CST (+0800)

correspond to a mount in Amonia, which as far as I understand as the same effect than K. Related to the species of Rhizocarpon, R. umbilicatum, according to the British Flora it grows on calcareous rocks, especially hard limestone and has spores in the range 18-28 × 10×16 um, thus a bit shorter then those I observed.

By: Jason Hollinger (jason)
2014-05-07 04:37:24 CST (+0800)

Never even heard of this genus before! Hmmm. Did you consider Rhizocarpon, too? There are two fair candidates there, too: R. petraeum and especially R. umbilicatum (see photos here) Did you happen to notice the K reaction of the epihymenium (“epithecium” in British Flora)? The two Rhizocarpon may have K+y reactions, and the Schadonia K+ “purplish-brown”. Just a thought…

Created: 2014-05-06 05:34:59 CST (+0800)
Last modified: 2014-05-06 05:36:41 CST (+0800)
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