Notes: Finally, after several observations of Pyxine specimens one fertile appeared. This fact, together with the macro features and the yellow medulla permits immediately to indicate the species: P. subcinerea. Such conclusion can be derived from the key for the genus in the Sonoran Flora (Ref. 1) , taking also into account that it was the only fertile species accepted to appear in Europe according to Ref. 2 (of which I could only read the abstract) as of 1983. Let me also refer that P. subcinerea is the unique of the genus appearing in the Portuguese checklist and that, according to recent records (already in this century) in the Azores Islands there are other three species: P. coccoes, P. farinosa and P. sorediata, where only the first one can be fertile (see Ref. 3).
In Ref. 3 one can also find photos of herbarium specimens of the two fertile species and the microscopy of P. coccoes. The comparison of the more detailed photos with that of my specimen seems a perfect match for P. subcinerea, while P. coccoes is much less sorediate and do not have visible pycnidia.
Taking the oportunity of having collected a sample I also made the microscopic analysis which, as far as I can see, reinforces the previous data. However, I observed with surprise that the spores are not so easy to describe as one can infer from the descriptions available in Ref. 1 (and also in Ref. 4): In fact, though most of the spores are 1-septate, the are other with no septum at all and others 2-3-septate, sometimes one septum being more “clear” than the others; also though most of them being ellipsoid there are others ovoid and of other forms; moreover, some of the spores have terminal apices lighter than the brown base colour and the tissues at the apices seem to be weaker than the rest of the spores, since appeared broken in the photos. I attach photos where these features can be seen.
Finally, let me refer that the dimension obatined for the spores, in average
Me = 16.7 × 6.5 um ; Qe = 2.6 (N=31);
in the ranges (11.8) 14.7 – 19.2 (21.2) x (4.7) 5.3 – 7.6 (8.5) um
completely agree with those given in Ref. 1 (or Ref. 4).
Ref. 1 (Sonoran Flora): Thomas Nash III et al. (Editors), Lichen Flora of the Greater Sonoran Desert Region, Vol. I, Arizona State Univ., 2002;
Ref. 2: R. Moberg, Studies on Physciaceae (Lichens) II. The Genus Pyxine in Europe, The Lichenologist 15(02):161 – 167, 1983;
Ref. 3: Azores Bioportal – http://www.azoresbioportal.angra.uac.pt/index.php?lang=en;
Ref. 4: CNALH – http://lichenportal.org/portal/taxa/index.php?taxon=52100.
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