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Rhizocarpon chioneum (Norman) Th. Fr.
Family: Rhizocarpaceae
[Catillaria chionea Norman,  more]
Rhizocarpon chioneum image
Life habit: lichenized (mutualistic with algal photobionts) thallus: crustose (crustaceous) – episubstratal – unspecified thallus: continuous, diffuse, effuse | cracked, fissured, fractured, rimose [th] upper surface: white(ish) [th upper surface]: pruinose [th marginal and upper surface] specific structures: absent ascomata: absent | present ascoma: apothecial, apothecioid – hymenial ascoma [mm]: (min) 1.0 ascoma: immersed, innate [ascm, if apoth] disc, mazaedium: plane, flat, flattened, expanded [ascm, if apoth] disc, mazaedium: black(ish) [ascm, if apoth] disc, mazaedium: epruinose [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: brown(ish) (if pale: fawn, tan; if mid: cinnamon) [ascm] paraphyses/-oids: present [ascm] epihymenium, epithecium: grey(ish) | red(dish) brown (pale: orange brown) asci: lecanoralean [asc] tholus: thickened [asc] tholus amyloidity (iodine reaction): present [asc] tholus amyloidity pattern: with amyloid cap (= Icmadophila-, Lecidea-, Pertusaria-types etc) ascospores: (median) 8.0 [asp] shape: ellipsoidal [asp] length [µm]: (low) 12.0 (high) 16.0 [asp] width [µm]: (low) 6.0 (high) 10.0 [asp] septa: present [asp] septa: transversely septate [asp] transversal septa: (median) 1.0 [asp] pigmentation: hyaline, colourless | medium brown, brownish | greenish grey [asp] perispore, epispore: thick, distincly halonate secondary metabolites: present secondary metabolites: stictic acid primary photobiont: present secondary photobionts (eg in cephalodia): absent primary photobiont: chlorophytaceous – trebouxiaceous, chlorococcoid.

substrate: rock – calcareous, calciferous, basic.