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Tetramelas pulverulentus (Anzi) A. Nordin & Tibell (redirected from: Buellia pulverulenta)
Family: Caliciaceae
[Buellia pulverulenta (Anzi) Jatta,  more]
Tetramelas pulverulentus image

Global occurrence: Eurasia – Asia Extratropical | Eurasia – Europe | Americas – North America (incl Mexico) | Arctic.  Substrate: lichens, lichenized fungi.  Life habit: lichenicolous (in/on lichens).  Thallus: crustose (crustaceous) – endosubstratal, inconspicuous, immersed; [th marginal and upper surface] specific structures: absent.  Ascomata: absent | present; ascoma: apothecial, apothecioid – hymenial; ascoma: sessile, superficial; [ascm, if apoth] disc, mazaedium: black(ish); [ascm] paraphyses/-oids: present; [ascm] paraphyses/-oid cells width [µm]: (low) 1.6 (high) 2.3; [ascm] paraphyses/-oid apical cells width [µm]: (min) 5.0.  Asci: lecanoralean; [asc] tholus: thickened; [asc] tholus amyloidity (iodine reaction): present; [asc] tholus amyloidity pattern: amyloid with acuate axial body towards the apex (= Bacidia-, Buellia-, Ramalina-types etc).  Ascospores: (min) 4.0(median) 8.0; [asp] shape: ellipsoidal; [asp] length [µm]: (min) 14.5 (low) 16.0 (high) 21.0 (max) 23.0; [asp] width [µm]: (low) 6.5 (high) 8.5; [asp] septa: present; [asp] septa: transversely septate; [asp] transversal septa: (min) 1.0(median) 3.0; [asp] pigmentation: medium brown, brownish; [asp] perispore, epispore: ornamented, rough, warted, striate, cracked.  Secondary metabolites: absent.  Primary photobiont: present, chlorophytaceous – trebouxiaceous, chlorococcoid.  Secondary photobionts (eg in cephalodia): absent.

Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus developing parasitically within the host plant, species of Physconia, Physcia, and Anaptychia, causing the appearance of a necral zone on the host, but with its own thallus within and of more dense smaller cells than those of the host, remaining as an endoparasitical lichen. Apothecia to 0.7 mm broad, at first immersed and spherical, becoming adnate and flattened; exciple dark brown, paraplectenchymatous, often with inclusions of crystals; disk black, sometimes with white pruina, shining; hypothecium brown to dark brown; epihymenium dark brown; hymenium 55-77 μm, hyaline, 1+ blue; asci clavate; paraphyses septate, branching in upper part, tips to 6 μm, and brown-capitate; spores biseriate, brown, 1-3-septate, ellipsoid, elongate, straight or slightly curved, the ends rounded, the surface slightly roughened, 14.5-23 x 6.5-8.5 μm.

This species is an endoparasite within members of the Physciaceae, and is especially recorded from Physconia muscigena. It appears to be circumpolar arctic and alpine. In North America it is known from Alaska, Colorado, Wyoming, and from the Northwest Territories.