Northwest Lichenologists

lichen identification

  • 06 Oct 2020 4:58 PM
    Message # 9288338

    For https://northwest-lichenologists.wildapricot.org/page-1816539/129626252#photo I think Pertusaria glaucomela. Perhaps someone can easily differentiate P. glaucomela and P. suboculata without P test.


    used keys to Pertusaria suboculata or P. glaucomela
    p 487 - McCune, Bruce. 2017. Microlichens of the Pacific Northwest. Volume 2: Keys to the Species.

    potential distinguishing characteristics:

    P. suboculata P+ O or R or P- ; P. glaucomelia P- (unfortunately! I don’t have P reagent)

    spore length of P. suboculata  > 21 µm; P. glaucomelia < 23   µm (mine average 25x14⇒P. suboculata)
    P. suboculata 20-30x10-15; P. glaucomela 10-23x7-14

    thallus both light gray (calling mine white), thickness overlaps with P. suboculata a bit thicker

    disk P. suboculata pruinose; not mentioned for P. glaucomelia (mine epruinose ⇒P. glaucomela)

    crenelate margin P. suboculata frequently so; P. glaucomelia slightly or entire (mine crenelate⇒P. suboculata)

    epihymenium of both K+ strong violet

    medulla P. suboculata K-; P. glaucomela K- or K+ yellowish or reddish brown (mine appears to be K-, difficult because so thin)

    largest apothecium 1.5mm
    LIAS has (min) 0.4 (low) 1.0 (high) 2.0

    my specimen has birefringent crystals soluble in K in hymenium

    found very few photos - P. glaucomela by McCune (Oregon Digital) somewhat resembles mine, iNaturalist photo Pertusaria glaucomela from Kodiak Island, AK, USA on July 26, 2017 at 10:39 PM by Masumi Palhof. On a Sitka Spruce twig · iNaturalist (id suggested by Toby Spribille) does not resemble mine

    “We distinguish P. suboculata [from P. oculata] solely on the the basis of its lack of isidia” - Spribille et al. p490 Bryologist 113 (3) 2020 Lichens and lichenicolous fungi of the Klondike Gold Rush National Historic Park, Alaska, in a global biodiversity context (which makes me lean towards P. glaucomela because P. oculata looks very different, e.g. see Lichen Herbarium O)

    Last modified: 06 Oct 2020 5:06 PM | Richard Droker
  • 07 Oct 2020 7:59 AM
    Reply # 9289442 on 9288338
    Bruce McCune (Administrator)

    Ooo, not using the P reagent for this ties one arm behind your back.


    Based on the info provided, I would guess P. suboculata. I give some weight to the spore sizes you reported. I also find that P. glaucomela is very common right on the coast, but I don't recall seeing it in subalpine situations. I have seen few P. suboculata, but those have been from Alaska and at mid to higher elevations in the mountains in OR/WA.

  • 07 Oct 2020 3:53 PM
    Reply # 9290509 on 9288338

    Thank you Bruce. I will confirm with P as soon as possible.

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