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Thelignya lignyota (Wahlenb.) P. M. Jorg. & Henssen
Family: Lichinaceae
[Porocyphus dispersus Å.E. Dahl]
Thelignya lignyota image
Life habit: lichenized (mutualistic with algal photobionts) thallus: crustose (crustaceous) – episubstratal – unspecified | squamulose (squamulous) | peltate, umbilicate thallus: granular, granulose, granulate [th] upper surface: black(ish) [th marginal and upper surface] specific structures: absent [th] morphol substructures (eg areoles, lobes, branches) width [mm]: (median) 0.15 ascomata: absent | present ascoma: apothecial, apothecioid – hymenial ascoma [mm]: (median) 0.3 (max) 0.6 ascoma: immersed, innate [ascm, if apoth] disc, mazaedium: concave | plane, flat, flattened, expanded | subconvex, slightly convex | convex [ascm, if apoth] margin excipular photobionts: absent [ascm] paraphyses/-oids: present [ascm] epihymenium, epithecium: green(ish) asci: prototunicate [asc] tholus: not thickened [asc] tholus amyloidity (iodine reaction): absent ascospores: (median) 8.0 [asp] shape: subglobose, subspherical | broadly ellipsoidal | ellipsoidal | oval [asp] length [µm]: (low) 7.0 (high) 12.0 [asp] width [µm]: (low) 5.5 (high) 9.0 [asp] septa: absent – spore lumen unilocular, monolocular [asp] pigmentation: hyaline, colourless [asp] perispore, epispore: not apparent conidiomata: absent | present conidia: cylindrical [co] length [µm]: (median) 2.5 secondary metabolites: absent primary photobiont: present secondary photobionts (eg in cephalodia): absent primary photobiont: cyanobacterial.

substrate: rock – siliceous, siliciferous, acidic | rock, stones, pebbles – unspecified.
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus of irregular papilliform areolae which may be dispersed or grouped, 1-2 mm broad, to 1 mm thick, blackish, often mixed with colonies of blue-green algae; hyphae of rounded cells in irregular arrangement. Apothecia entirely immersed in thallus with urceolate disk and narrow ostiole; margin of parallel hyphae, 10 μm thick below, 25 μm above; epithecium green or olive-green; hymenium 65-120 μm, I—; paraphyses net-like anastomosing, 1-1.5 μm, tips slightly thickening; asci cylindrical; spores 8, simple, hyaline, ovate, 8-10 x 5.5-7 μm.

This species grows on moist rocks along brooks. It is very rare, being known from Fredrik-shaab District in Greenland, Sweden, and Timber-creek Campground, Grand County, Colorado. With this disjunct range, it should be sought in the American Arctic.

The green epithecium is a very diagnostic character.