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Thelidium pyrenophorum (Ach.) Mudd
Family: Verrucariaceae
[Involucrothele pyrenophora (Ach.) Servít,  more]
Thelidium pyrenophorum image
Stephen Sharnoff  
Life habit: lichenized (mutualistic with algal photobionts) thallus: crustose (crustaceous) – endosubstratal, inconspicuous, immersed | crustose (crustaceous) – episubstratal – unspecified thallus: continuous, diffuse, effuse | granular, granulose, granulate | cracked, fissured, fractured, rimose [th] upper surface: grey(ish) | brown(ish) (if pale: fawn, tan; if mid: cinnamon) | white(ish) | brown(ish) grey | grey(ish) brown [th marginal and upper surface] specific structures: absent ascomata: absent | present ascoma: perithecial, perithecioid – hymenial ascoma [mm]: (min) 0.24 (low) 0.3 (high) 0.7 (max) 1.0 ascoma: subsessile, subimmersed, adnate, semi-immersed, emergent [ascm, if apoth] margin surface; [if perith] periostiolar area, ostiole, involucrellum: black(ish) | grey(ish) | brown(ish) (if pale: fawn, tan; if mid: cinnamon) | brown(ish) black [ascm, if apoth] margin excipular photobionts: absent [ascm] paraphyses/-oids: absent asci: fissitunicate – bitunicate [asc] tholus: thickened [asc] tholus amyloidity (iodine reaction): absent ascospores: (median) 8.0 [asp] shape: ellipsoidal | elongate-fusiform, ellipsoidal-fusiform [asp] length [µm]: (min) 16.5 (low) 21.0(median) 24.8 (high) 28.5 (max) 36.5 [asp] width [µm]: (min) 7.5 (low) 10.0(median) 11.7 (high) 13.5 (max) 16.5 [asp] septa: present [asp] septa: transversely septate [asp] transversal septa: (median) 1.0 [asp] pigmentation: hyaline, colourless [asp] perispore, epispore: not apparent secondary metabolites: absent primary photobiont: present secondary photobionts (eg in cephalodia): absent primary photobiont: chlorophytaceous – trebouxiaceous, chlorococcoid.

substrate: rock – siliceous, siliciferous, acidic | rock – calcareous, calciferous, basic | rock, stones, pebbles – unspecified.