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Verrucaria pinguicula A. Massal.
Family: Verrucariaceae
[Involucrothele pinguicula (A. Massal.) Servít,  more]
Verrucaria pinguicula image
André Aptroot  

Global occurrence: Eurasia – Asia Extratropical | Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate: rock – calcareous, calciferous, basic | rock, stones, pebbles – unspecified.  Life habit: lichenized (mutualistic with algal photobionts).  Thallus: crustose (crustaceous) – endosubstratal, inconspicuous, immersed | crustose (crustaceous) – episubstratal – unspecified; thallus: continuous, diffuse, effuse | cracked, fissured, fractured, rimose; [th] upper surface: brown(ish) (if pale: fawn, tan; if mid: cinnamon) | white(ish) | green(ish) brown (olive brown); [th marginal and upper surface] specific structures: absent; [th] morphol substructures (eg areoles, squamules): contiguous, coherent (throughout the thallus); [th] morphol substructures (eg areoles, lobes, branches) upper surface: smooth, plane.  Ascomata: absent | present; ascoma: perithecial, perithecioid – hymenial; ascoma [mm]: (low) 0.14(median) 0.2 (high) 0.44; ascoma: subsessile, subimmersed, adnate, semi-immersed, emergent; [ascm, if apoth] margin surface; [if perith] periostiolar area, ostiole, involucrellum: black(ish); [ascm, if apoth] margin excipular photobionts: absent; [ascm, if apoth] subhymenial layers, hypothecium; [if perith] basal excipulum: hyaline, colourless | hyaline yellow; [ascm] paraphyses/-oids: absent.  Asci: fissitunicate – verrucarialean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent.  Ascospores: (median) 8.0; [asp] shape: ellipsoidal; [asp] length [µm]: (min) 12.0 (low) 13.5(median) 15.8 (high) 18.0 (max) 22.0; [asp] width [µm]: (min) 5.0 (low) 5.5(median) 6.9 (high) 8.5 (max) 11.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless; [asp] perispore, epispore: not apparent | thin, thinly halonate.  Secondary metabolites: absent.  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.