Slideshow image
Acarospora impressula Th. Fr.
Family: Acarosporaceae
[Acarospora atrata Hue,  more]
Acarospora impressula image

Global occurrence: Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate: rock – siliceous, siliciferous, acidic.  Life habit: lichenized (mutualistic with algal photobionts).  Thallus: crustose (crustaceous) – episubstratal – unspecified; thallus: cracked, fissured, fractured, rimose | compartimentized – areolate, squamulate; [th] upper surface: brown(ish) (if pale: fawn, tan; if mid: cinnamon) | black(ish) brown; [th upper surface]: epruinose; [th marginal and upper surface] specific structures: absent; [th] morphol substructures (eg areoles, lobes, branches) width [mm]: (low) 0.4(median) 0.7 (high) 1.0 (max) 1.5; [th] morphol substructures (eg areoles, lobes, branches) upper surface: subsquamulose.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma [mm]: (median) 0.4; [ascm, if apoth] disc, mazaedium: concave | plane, flat, flattened, expanded; [ascm] paraphyses/-oids: present; [ascm] paraphyses/-oid cells width [µm]: (low) 1.5 (high) 2.0.  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent; [asp] length [µm]: (low) 3.0 (high) 5.0; [asp] width [µm]: (min) 1.5 (low) 2.0 (high) 2.5; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless; [asp] perispore, epispore: not apparent.  Primary photobiont: present; chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobiont (eg in cephalodia): absent.