Pyrenidium actinellum s. l.

Unlichenized lichenicolous Ascomycota

    Thallus invisible, fungus and host hyphae being mixed. Ascomycota visible as perithecoid pseudotheca, 0.15-0.20 mm diam., globose to subconical, more or less immersed in host thallus, prominent at first, sometimes clustered and then forming minute dark to blackish 'galls'. Ascii cylindrical, 60-90 x 12-20 µm, 4-spored (seldom 8-spored according to literature, not observed in our prospection area). Ascospores pale brown at first, then brown-blackish when mature, ellipsoid, straight to slightly curved, 3-septate, narrowed at septa level, the 2 central -with a vacuole- larger than 2 distal cells , distal cells hemispherical, paler, 20-25 x 7-10 µm according to our measures (19-30 x 8-11 according to literature).This species is found on numerous lichens: crustose, foliose as well as fruticolous where it forms small black galls. The specimen presented here were found on Phaeophyscia orbicularis where they may form small blackish galls on host soralia. N.B. This 'species' is considered here sensu lato since the Nylander type was found on Leptogium teretiusculum and it cannot be excluded that different taxa may exist in relation to different hosts. See Buelliella physiicola, which is much more common on  Phaeophyscia orbicularis and of which the aspect of pseudotheca suggests apothecia, open when mature, and with colourless to pale brown 1-septate ascospores.*