Micarea intrusa (Th. Fr.) Coppins & H. Kilias

in Coppins, Bull. Br. Mus. Nat. Hist., Bot. 11, 2: 138, 1983. Basionym: Lecidea intrusa Th. Fr. - Bot. Not.: 152, 1867.
Synonyms: Carbonea intrusa (Th. Fr.) Rambold & Triebel; Catillaria intrusa (Th. Fr.) Th. Fr.; Conida intrusa (Th. Fr.) Sacc. & D. Sacc.; Lecidea aphanoides Nyl.; Lecidea contrusa Vain. nom. illegit.; Lecidea melaphana Nyl.; Lecideopsis intrusa (Th. Fr.) Zopf; Scoliciosporum intrusum (Th. Fr.) Hafellner
Distribution: N - Frl, TAA.
Description: Thallus crustose, black or black brown, areolate-granulose, forming insular, small patches on and inbetween other crustose lichens. Apothecia biatorine, 0.15-0.4 mm across, black, often glossy, adnate, with a convex disc and an indistinct, soon excluded proper margin. Proper exciple brownish in outer part, paler within, of radiating, branched and anastomosing hyphae; epithecium scarcely differentiated from the hymenium, olive-green to bluish green, K+ intensifying green, N+ red to pale violet; hymenium colourless or pigmented in upper part, not inspersed, 40-50 μm high, the hymenial gel K/I- (but gel and outer layer of empty asci K/I+ blue); paraphyses numerous, branched and anastomosing, c. 1.5 μm thick at mid-level, with only slightly enlarged tips; hypothecium colourless to olivaceous, up to 200 μm high, in the upper part sometimes orange and K+ purple (Intrusa-yellow pigment). Asci 8-spored, clavate to broadly cylindrical, the wall lecanoralean, strongly thickened at apex and forming a tholus, with a broad ocular chamber; ascal gel, outermost wall layer and tholus K/I+ blue, with a broad, more or less cylindrical, non-amyloid axial body. Ascospores 1-celled to 1(-2)-septate, ellipsoid to fusiform, sometimes slightly curved, hyaline or brownish when overmature, (7-)12-17(-19) x 4-6 μm. Photobiont chlorococcoid, the cells mostly (7-)10-18(-21) μm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a probably circumpolar, arctic-alpine species, invading the thalli of different crustose silicicolous lichens; for further details see Hafellner (2004). According to Miadlikowska & al. (2014) this species does not belong to Scoliciosporum and, pending further study, should be best treated as a member of Micarea.
Growth form: Crustose
Substrata: rocks
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
paras silicicolous crustose lichens

Commonnes-rarity: (info)

Alpine belt: extremely rare
Subalpine belt: extremely rare
Oromediterranean belt: absent
Montane belt: absent
Submediterranean belt: absent
Padanian area: absent
Humid submediterranean belt: absent
Humid mediterranean belt: absent
Dry mediterranean belt: absent

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model
Herbarium samples

Jason Hollinger – Public Domain – Source: https://lichenportal.org/cnalh/collections/individual/index.php?occid=3768162
Canada, Ontario, Sleeping Giant Provincial Park, Talus Lake

Jason Hollinger – Public Domain – Source: https://lichenportal.org/cnalh/collections/individual/index.php?occid=3768162
Canada, Ontario, Sleeping Giant Provincial Park, Talus Lake


Coppins, BJ (1983) A taxonomic study of the lichen genus Micarea in Europe. Bulletin of the British Museum (Natural History), Botany Series https://nhm2.uio.no/botanisk/lav/RLL/PDF1/R3527.pdf

Lipnicki, L (1993) Materialy do flory porostow Drawienskiego Parku Narodowego [A contribution to the lichen flora of the Drawienski National Park]. Fragmenta Floristica et Geobotanica

Aptroot, A/ Diederich, P/ Serusiaux, E/ Sipman, HJM (1997) Lichens and Lichenicolous Fungi from New Guinea.

Berger, F (2000) Beitrag zur Kenntnis der Flechten un lichenicolen Pilze Islands. Acta Botanica Islandica http://utgafa.ni.is/Acta-Botanica-Islandica/Acta-Botanica-Islandica-13/Acta-Botanica-Islandica-13-3.pdf

Hinds, JW/ Fryday, AM/ Dibble, AC (2002) Three additions to the lichen flora of North America from Mt. Katahdin, Maine. Evansia