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Lobothallia melanaspis (Ach.) Hafellner
Family: Megasporaceae
[Aspicilia melanaspis (Ach.) Poelt & Leuckert,  more]
Lobothallia melanaspis image

Global occurrence: Oceania – Australasia | Eurasia – Europe | Americas – North America (incl Mexico).  Substrate: rock – siliceous, siliciferous, acidic | rock, stones, pebbles – unspecified.  Life habit: lichenized (mutualistic with algal photobionts).  Thallus: placodioid-crustose, placodioid-foliose; [th] upper surface: grey(ish) | green(ish) | blue(ish) grey | white(ish) grey | brown(ish) green (olivaceous, olive green); [th upper surface]: epruinose | pruinose; [th marginal and upper surface] specific structures: absent; [th] morphol substructures (eg areoles, lobes, branches) width [mm]: (low) 0.4 (high) 0.8 (max) 1.0; [th] lower surface: grey(ish); [th lower surface] specific structures: absent.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma [mm]: (low) 0.5 (high) 1.5 (max) 1.8; ascoma: sessile, superficialj; [ascm, if apoth] disc, mazaedium: plane, flat, flattened, expanded | subconvex, slightly convex | convex; [ascm, if apoth] disc, mazaedium: brown(ish) black | black(ish) brown | red(dish) brown (if pale: orange brown); [ascm, if apoth] disc, mazaedium: epruinose; [ascm, if apoth] subhymenial layers, hypothecium; [if perith] basal excipulum: hyaline, colourless; [ascm] paraphyses/-oids: present; [ascm] paraphyses/-oid apical cells width [µm]: (min) 3.0; [ascm] epihymenium, epithecium: yellow(ish) brown | red(dish) brown (pale: orange brown).  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): absent.  Ascospores: (low) 4.0 (high) 8.0; [asp] shape: subglobose, subspherical | broadly ellipsoidal; [asp] length [µm]: (min) 10.0 (low) 13.5 (high) 18.5; [asp] width [µm]: (min) 6.0 (low) 8.0 (high) 10.0 (max) 13.0; [asp] septa: absent – spore lumen unilocular, monolocular; [asp] pigmentation: hyaline, colourless; [asp] perispore, epispore: not apparent.  Conidiomata: absent | present.  Conidia: bacilliform, bacillary; [co] length [µm]: (low) 4.5 (high) 6.0.  Secondary metabolites: absent | present, norstictic acid | unknown/unidentified compound(s).  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.

Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus upper side grayish olive to dark olive, sometimes glaucous, epruinose, lobate, close to the substratum, the center more or less areolate, the margins distinctly radiate-lobate, the lobes very convex to almost cylindrical; corticate above and below.

Apothecia to 2 mm broad, adnate with entire margin concolorous with thallus; disk brown or black-brown, sometimes pruinose; hypothecium hyaline, 1+ pale blue; epihymenium pale or brown, HC1-; hymenium 70-75 µm, 1+ brown; paraphyses coherent, thick, over 2.5 µm, upper part moniliform, 4-6 µm with the uppermost cell globular; spores 8, ellipsoid, 8-14 x 5-9 µm. Conidia short, cylindrical, 5-6 µm.

Reactions: medulla K+ red, P+ orange, I-.

Contents: norstictic acid, placodin, sometimes only in trace amounts (Hermann etal. 1973).

This species grows on acid rocks. It is circumpolar arctic, boreal and temperate, ranging south in North America to Arizona.

Although recent European lichcnologists place this species and A. alphoplaca in this genus, there is room for question as to whether this is the best disposition, as these have short, cylindrical conidia and this species does not have the characteristic "aspicilia-green” HCL reaction. A. meianaspis differs from A. alphoplaca in its contents of placodin as well as in possessing rather trace amounts of norstictic acid, so that it often yields negative reactions.