{{Use dmy dates|date=October 2023}} {{Short description|Species of lichen}} {{Speciesbox | image = Calicium glaucellum 206835030.jpg | image_alt = | image_caption = | status = G4 | status_system = TNC | status_ref = <ref name=NS>{{cite NatureServe |id=2.127056 |title=''Calicium glaucellum'' |access-date=27 May 2025}}</ref> | taxon = Calicium glaucellum | authority = Ach. (1803) | synonyms = }}
'''''Calicium glaucellum''''' is a crustose lichen that is found growing on trees throughout much of the world. The species is similar to ''Calicium abietinum.''<ref name="fact">{{cite web|url=https://www.blm.gov/or/plans/surveyandmanage/files/sfs-li-calicium-abietinum-2011-06.pdf|title=Calicium abietinum Species Fact Sheet|accessdate=24 July 2017|date=31 December 2008|publisher=Bureau of Land Management|archive-date=2 March 2017|archive-url=https://web.archive.org/web/20170302163620/https://www.blm.gov/or/plans/surveyandmanage/files/sfs-li-calicium-abietinum-2011-06.pdf|url-status=dead}}</ref>
The species is commonly found in northern boreal to temperate zones in North, Central, and South America<ref name="fact2">{{cite web|url=http://lichenportal.org/portal/taxa/index.php?taxon=52538&taxauthid=1|title=Calicium glaucellum Species Fact Sheet|accessdate=25 July 2017|date=31 December 2008|publisher=Bureau of Land Management}}</ref> and the South West region of Western Australia.<ref name="FloraBase">{{FloraBase|name=Calicium glaucellum|id=27618}}</ref>
== Morphology == This lichen has a lichenized life habit. Its thallus is typically immersed, but can rarely be superficial and then thin, indistinct, and dark grayish green with a granular appearance.<ref name=":0">{{Cite web |title=Consortium of Lichen Herbaria - Calicium glaucellum |url=https://lichenportal.org/portal/taxa/index.php?tid=52538&taxauthid=1&clid=201 |access-date=2024-03-14 |website=lichenportal.org |archive-date=14 March 2024 |archive-url=https://web.archive.org/web/20240314203637/https://lichenportal.org/portal/taxa/index.php?tid=52538&taxauthid=1&clid=201 |url-status=live }}</ref>
The apothecia of C. glaucellum usually have a faint white pruina, at least along the edge (upper part) of the exciple and below the capitulum. They are 0.5-1 mm tall and 4-9 times as high as the width of the stalk.<ref name="fact" /><ref name=":0" />
The stalk is shiny black, 0.11-0.17 mm wide, and consists of blackish brown to dark aeruginose, irregularly interwoven and strongly sclerotized hyphae that become paler towards the surface. The outermost layer of the stalk is paler and has a distinct, gelatinous, hyaline coat.<ref name=":0" />
The capitulum is obovoid to lenticular, measuring 0.23-0.34 mm in diameter. The exciple is dark brown to aeruginose, composed of elongated to almost isodiametric sclerotized hyphae that are paler in the outer part and distinctly anticlinally arranged. The hypothecium is dark brown with a flat or slightly convex upper surface.<ref name=":0" />
The asci are cylindrical, 35-41 μm x 3.5-4.5 μm, and contain uniseriate spores. The ascospores are ellipsoid, 9-13 x 4-6.5 μm, with a coarse irregular ornamentation of cracks and ridge fragments. Semi-mature spores have a very irregular sulcate pattern, mainly with longitudinally arranged ridges disrupted by irregular cracks.<ref name=":0" />
Pycnidia are frequently present, producing narrowly cylindrical conidia that are 4-5 x 0.8 μm.<ref name=":0" />
== Chemistry == Spot tests show the thallus is K+ dull yellow, C−, KC−, P−, and the apothecia are I−.<ref name=":0" />
The secondary chemistry can vary, with either no detected substances or the presence of sekikaic acid (major), 2-O-methylsekikaic acid (minor), and 4-O-methylhypoprotocetraric acid.<ref name=":0" />
== Ecology and distribution == Calicium glaucellum grows on old stumps, standing or fallen wood of both coniferous and deciduous trees, and more rarely on bark. It often occurs in exposed situations.<ref name=":0" />
The species is found in the northern boreal to temperate zones of North, Central, and South America,<ref name="fact2" /> as well as Australasia.<ref name="FloraBase" /> In the Sonoran region, it has been reported from southern California and Chihuahua.<ref name=":0" />
== Distinguishing features == Calicium glaucellum is recognized by its rather short-stalked apothecia, the presence of a white rim along the edge of the exciple, the usually immersed thallus, and the medium-sized spores with an ornamentation of irregular ridges and cracks. It is very similar to C. abietinum but differs in having a more pronounced white pruina, black stalks instead of brownish ones, and slightly smaller spores with a different ornamentation pattern.<ref name=":0" />
==References== {{Reflist}}
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glaucellum Category:Lichen species Category:Lichens described in 1803 Category:Lichens of Australia Category:Taxa named by Erik Acharius