Slideshow image
Umbilicaria leiocarpa DC.
Family: Umbilicariaceae
[Agyrophora leiocarpa (DC.) Gyeln.]
Umbilicaria leiocarpa image
Lucy Taylor  
Life habit: lichenized (mutualistic with algal photobionts) thallus: peltate, umbilicate; thallus: continuous, diffuse, effuse | cracked, fissured, fractured, rimose | compartimentized – areolate, squamulate; [th] upper surface: grey(ish) | brown(ish) (if pale: fawn, tan; if mid: cinnamon) | white(ish) | black(ish) brown [th upper surface]: pruinose [th upper surface] pruina: scarce, sparse, fine | dense [th marginal and upper surface] specific structures: absent [th] morphol substructures (eg areoles, lobes, branches) width [mm]: (low) 25.0 (high) 80.0 [th] morphol substructures (eg areoles, squamules): contiguous, coherent (throughout the thallus) [th] morphol substructures (eg areoles, lobes, branches) upper surface: smooth, plane | verrucose, warted | rugose, plicate, folded, pustulate, faveolate, wrinkled [th] lower surface: black(ish) | grey(ish) [th lower surface] specific structures: present [th lower surface] rhizines, rhizoid structures: absent ascomata: absent | present ascoma: apothecial, apothecioid – hymenial ascoma [mm]: (low) 1.5 (high) 2.0 ascoma: pedicellate, stipitate, pedunculate, stalked [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: black(ish) [ascm] paraphyses/-oids: present [ascm] paraphyses/-oid cells width [µm]: (low) 1.5 (high) 2.5 [ascm] paraphyses/-oid apical cells width [µm]: (low) 2.5 (high) 3.5 [ascm] epihymenium, epithecium: black(ish) asci: lecanoralean [asc] tholus: thickened [asc] tholus amyloidity (iodine reaction): present [asc] tholus amyloidity pattern: entirely amyloid (= Catillaria-, Teloschistes-types etc) ascospores: (median) 8.0 [asp] shape: ellipsoidal [asp] length [µm]: (low) 12.0 (high) 14.5 [asp] width [µm]: (low) 4.0 (high) 5.0 [asp] septa: absent – spore lumen unilocular, monolocular [asp] pigmentation: hyaline, colourless | pale brown [asp] perispore, epispore: not apparent conidiomata: absent | present conidia: cylindrical [co] length [µm]: (low) 2.5 (high) 5.0 secondary metabolites: present secondary metabolites: norstictic acid primary photobiont: present secondary photobionts (eg in cephalodia): absent primary photobiont: chlorophytaceous – trebouxiaceous, chlorococcoid.

substrate: rock – siliceous, siliciferous, acidic | rock, stones, pebbles – unspecified.
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus umbilicate, mono- or polyphyl-lus, usually deeply incised and folded; margins fragile and slightly perforate; upper side rough-ribbed becoming chinky areolate toward the margins, the center pruinose over the umbo, dull, dark brown to brown-black; lower surface smooth to subpapillose, sooty roughened, the margins paler, tiny areolate.

Thallus ca. 250 µ thick; upper cortex 33 µ, medulla 33 µ, lower cortex about 83 µ.

Apothecia stipitate, to 2 mm broad, disk flat, black, margin even, dark; hypothecium black; hymenium 50 µ, brownish; paraphyses unbranched, septate, the tips capitate, to 2.4 µ; spores simple, hyaline, middle dark stained, 4-4.8 X 12-15 µ.

Reactions: not checked.

Contents: unknown.

This is a rare bipolar species known only from western Greenland (Inglefield Land in the north and Igdlut in the south central part) and northern Somerset Island in North America. In Europe it occurs in Norway, Switzerland, and Hungary. I have not seen this species.