Collection location: Serra de São Mamede, Portugal [Click for map]
According to the British Flora in the British islands, and by extension I believe the same can happen here, there are only four_Caloplaca spp._ satysfying the following conditions:
- Grow on (calcareous or siliceous) rocks;
- Thallus entirely corticate without isidia, blastidia or soralia;
- Disc yellow, orange or rust coloured when dry; Thalline margin disappearing with age;
- Cortex white or grey, K- (only discs usually K+ purple)
- Ascospore septum >1/8 lenght of spore;
Namely , C. arenaria, C. ceracea, C. crenularia, C. holocarpa agg.. To note that the last one is an aggregate of taxa, that the authors consider not to be yet completely resolved.
It happens that quite recently I believe to have found three of these species, only C. arenaria being absent from those observations.
In this observation only C. ceracea is considered and the others will be considered soon.
In addition to the previously mentioned features, we have for this specimen:
- Grew on siliceous rock;
- A roughened areolate surface, distinctly grey;
- Discs orange-brown coloured, matt; Apothecia with a proper margin yellow-orange;
- A dense layer of a green alga below the hialine hypothecium;
- Paraphyses slightly swolen at the apices;
- Ascospores with average dimensions: Me = 14.3 × 8.1 um ; Qe = 1.8; Septum with more than 1/3 of the lenght of the ascospore.
[Note: I suspect that these values are a bit inflated as a result of the addition of a drop of K to the slide.]
The dense layer of the alga below the hypothecium is considered a distinguish feature of this species and permits to separate it from the similar ones.
Attached one can find a set of photos illustrating all the properties mentioned above.
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