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Willeya diffractella (Nyl.) Mull. Arg. (redirected from: Staurothele tenuissima)
Family: Verrucariaceae
[Endocarpon diffractellum (Nyl.) Gueidan & Cl. Roux,  more]
Willeya diffractella image
Stephen Sharnoff  

Thallus pale brown to pale grayish brown, usually continuous, rimose-areolate, and rather smooth.  Pertihecia embedded in thallus except for the conspicuous black summits that are visible at the surface as black dots with a clearly indented ostiole; involucrellum spreading and distinct from exciple (as shown in Fig. 17a); abundant algal cells (usually spherical) in the hymenial cavity; spores colorless, (4-)8 per ascus, 15-28 X 9-12 µm.  HABITAT: Typically on lime-containing rocks, but sometimes on gneiss or even granite; usually in shaded habitats.  COMMENTS:  This is by far the most common 8-spored Staurothele, but the spores are often hard to count because finding a full ascus is not easy.  Look for immature asci with small, developing spores.