Observation 72707: Hysterium Pers.

When: 2011-07-07

Collection location: Sintra, Portugal [Click for map]

Who: zaca

No specimen available

This observation is relative to the lirellae lichen with dark apothecia. The other lichen that appears in the photos was considered in a different observation (MO72706), but it is convenient to read the notes that follow.
This identification was very curious because it involves two species of lichens with very different characteristics: a Lecanora and a Graphidaceae in a broad sense, which later I conclude to belong to the genus Opegrapha. In fact, I’m almost certain I got the end result, but is always some doubt. Let me explain:
Apparently there was no distinction between the thallus of the two lichen. In the field I made the spot tests to the thallus and got the following results: C-, K + red, KC + red (fading). At home, with the help of Generic key to “script” lichens (from Sonoran Flora) posted by Jason in a comment to Observation MO68273, I made the choices in the key as follows:
1b. spores septate or muriform (—>)
2b. spores muriform or septate with blocky cells and spore walls evenly thickened (—>)
3b. spores 3- or more-septate or muriform (—>)
5b. ascomata without thalline margin . . . Opegraphaceae s. lato.
Next I did the microscopy and after some searching I came to the conclusion that the data fit perfectly to the genus Opegrapha and, in particular, to the species O. herbarum, with the exception of the results of chemical tests, that for this species are (according to “CNALH”): C-, K-, KC-. I suspected then that the results obtained initially were for the Lecanora and I essayed the K reaction in a place of the thallus where there was no apothecia of the lirellae. The result was conclusive: K + red (pure). This allowed me to identify also the species of Lecanora (see MO72706).
Here are the results obtained for the dimensions of the spores:
(19.2) 20 – 23.5 (24.1) x (4.9) 6 – 7.3 (7.9) µm
Q = (2.6) 3 – 3.7 (3.9) ; N = 35
Me = 21.5 × 6.6 µm ; Qe = 3.3.


Apothecia in detail.

Proposed Names

-32% (2)
Used references: CNALH, Irish lichens.
Based on microscopic features
Based on chemical features
38% (1)
Recognized by sight
Based on microscopic features
Based on chemical features

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= Observer’s choice
= Current consensus


Add Comment
Thanks, Henk-Jan,
By: zaca
2014-02-27 21:01:49 EST (-0500)

for your comment. Your remark about the coloured is pertinent and now I recognize that you are right about the genus: Hysterium. Concerning the species, the form of liralae and the shape and dimension of the spores fit very well in H. angustatum as you observed in the comment. Is there any other similar species that lead you to vote for Hysterium and not for H. angustatum?
Thanks again,

Hysterium angustatum
By: Henk-Jan van der Kolk (henkjanvdkolk)
2014-02-27 12:51:46 EST (-0500)

This is not a lichen, but an (free-living) ascomycete: Hysterium angustatum. The ascospores of Opegrapha are colorless.

Regards, Henk-Jan

Created: 2011-07-26 17:32:58 EDT (-0400)
Last modified: 2014-02-27 21:03:35 EST (-0500)
Viewed: 131 times, last viewed: 2019-02-14 12:49:00 EST (-0500)
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