Observation 240524: Lecania A. Massal.

When: 2016-05-21

Collection location: Paimogo, Lourinhã, Portugal [Click for map]

Who: zaca

No specimen available

Notes:
Growing on a piece of rock in a calcareous habitat, close to the sea border.
My impression on the field was that this could be a weird Diplotomma; Nevertheless, I collected a sample that just analyzed. Starting with a section of an apothecium immediatly realized to be in presence of something completely different than thought. Going further the KOH reaction on the section was negative, simply enhanced the yellowish coloration of a part of the hymenium. Further, pressing the slide could see paraphyses with dark tips but not much enlarged and small asci, clavate and somewhat flexuosus, containing 8 hyaline 1-septate spores inside. The asci apex showed a big tholus and a prominent apical beak, like that in Bacidia-type asci. This was unexpected and the first task was to establish the genus of this specimen. Using Ref. 2 the answer was Lecania!
My knowledge of this genus is very limited and I only identified before one of its species, but not based on microscopic properties. After noting the spores form – ellipsoid to fusiform many of them with a cell bigger than the other, sometimes but not always fusiform – and their dimensions:
(10.7) 11.3 – 12.9 (14.1) × (3.7) 4.3 – 5 (5.3) µm
Q = (2.3) 2.4 – 2.9 (3) ; N = 22
Me = 12.1 × 4.6 µm ; Qe = 2.6
went to the keys. Before it is worth mention that many small crystals were found in the slides, that to a certain extent caused several difficulties in the observation of asci and spores.
In the Sonoran Flora Vol. 2, I was lead to a group of species formed by L. chalcophila, L. rayiana and L turicensis. The same exercise in the British Flora leads to L turicensis, if considering white pruinose thallus or apothecia, or L. sylvestris, in the other case and taking into account the calcareous substrata. In my opinion the opinion the thallus and the apothecia are epruinose or only slightly pruinose.
It should be mentioned that L. chalcophila and L. rayiana are not mentioned in the British Flora and that L. sylvestris is not mentioned in the Sonoran Flora.
The next step was the IKI staining of the asci, which gave another surprise; I think that the asci are of the “Biatora-type”, characterized by an ascus tholus that has a more or less conical ocular chamber and a high conical axial body surrounded by an amyloid zone darker than the rest of the stained apex. If this is so, than most of the above cited species are ruled out (by having “Bacidia-type asci”, according to the Sonoran Flora) with the exception of L. sylvestris, according to Ref. 3. Maybe this point has to be clarified.
Finally, let me mention that, according to Ref. 3, L. sylvestris has a thin and granular, sometimes immersed, thallus and that the spores have 11.1–11.4 × 2.9–3.4 mm, being ellipsoid to fusiform, but the sketch illustrating they form only shows fusiform ones. In my specimen most probably the thallus, which is not immersed, should be classified as areolate and the range for the spores dimensions are bigger than that.

Images

Microscopy: Apothecial section and its KOH reaction;
Microscopy: Hymenium;
Microscopy: Asci (x1000, in KOH);
Microscopy: Asci and spores (x1000, in KOH);
Microscopy: Asci staining with IKI, after pretreatment in KOH (x1000, in KOH).

Proposed Names

87% (1)
Used references: Ref. 1 – British Flora;
Ref. 2 – Sonoran Flora, Vol. 2;
Ref. 3 – R.R. Næsborg: Taxonomic revision of the Lecania cyrtella group based on molecular and morphological evidence, Mycologia, 100(3), 2008, pp. 397–416; available at http://www.mycologia.org/content/100/3/397.full.pdf
Based on microscopic features
29% (1)
Recognized by sight

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= Observer’s choice
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