Observation 218498: Punctelia bolliana (Müll. Arg.) Krog

When: 2015-07-25

Collection location: St. Cloud, Minnesota, USA [Click for map]

45.5056° -94.3401° 361m

Who: J-Dar

Specimen available

Mixed hardwood forest, on oak trunk bark.
Thallus large, foliose, orbicular, blue-grey. Lobes weakly pruinose, often with lobules. Thallus underside pale tan throughout, with simple rhizines, white when young to black with white tips (black rhizines give impression of black lower cortex, but it is tan even in center). Thallus upper surface with round pseudocyphellae. Thallus upper cortex K+Y, C-. Medulla C-, K-, KC- (4 specimens tested). Soredia and isidia absent. Apothecia common to occasional, deeply concave when young, disk tan, margins often with pseudocyphellae, cracking in old age.


Some sort of infection or something causing white spots.
The Punctelia of this observation is the blueish lichen in the center.

Proposed Names

28% (1)
Recognized by sight
56% (1)
Eye3 Eyes3
Based on chemical features: Medulla C-, KC-

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Not completely
By: Jason Hollinger (jason)
2015-10-11 14:38:09 PDT (-0700)

Conidia is by far the most reliable discriminant, but see pg 434 vol II Sonoran Flora, notes under P. hypoleucites.

Have that!
By: J-Dar
2015-10-11 14:26:54 PDT (-0700)

Well, I have the compound scope now, but I haven’t gotten it calibrated for measurements yet. Next project, and I’ll see what I can do to figure this one out. Please tell me there is more than just conidia length separating these species!

Will need to measure conidia length, too, unfortunately
By: Jason Hollinger (jason)
2015-10-11 13:58:36 PDT (-0700)

P. hypoleucites – conidia > 8 µm long
P. graminicola – conidia < 8 µm long

Generally very unambiguous, but does require a microscope, alas. :(

Created: 2015-10-11 13:51:25 PDT (-0700)
Last modified: 2015-12-02 20:45:16 PST (-0800)
Viewed: 30 times, last viewed: 2017-06-20 21:02:27 PDT (-0700)
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