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Calicium on hawthorn

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  • May 4, 2025 at 11:06 am #33033
    Glos lichens

      Help! I can’t fit a name to this Calicium, from very well-lit Crataegus bark at Westonbirt bioblitz (Gloucestershire) last weekend.

      Juliet

      May 5, 2025 at 7:11 pm #46572
      Neil Sanderson
      Senior Moderator

        I would think that is a small Calicium glaucellum, certainly keys out as that from what I can see on your photos, but some measurements of spore and asci size would help. The white pruina on the head is often absent from Calicium glaucellum and is also sometimes present on other species anyway e.g. Calicium lenticulare.

        (Calicium lenticulare: that test has the iodine applied into water, which is indicated by “I+ dark blue to black” It would be “K/I+ blue” if K was required first, but K/I probably works too).

        Neil

        May 21, 2025 at 2:32 pm #46573
        Glos lichens

          Thanks Neil

          I’ve had another look at my specimen assuming it is glaucellum. The ring of pruine is visible on a few of the aps.

          Measuring the asci is tricky, because mature aps just squash to a mess of spores, so here is one where the head is just starting to swell.

          Asci length measured 39-42 microns.

          The spores are so variable in length and shape I can’t see how to pick the normal range.

          Can anyone give me guidance on observing spore ornamentation, please.

          Juliet

          May 24, 2025 at 12:25 pm #46574
          Neil Sanderson
          Senior Moderator

            Juliet

            Seems OK for Calicium glaucellum.

            Quote:

            Can anyone give me guidance on observing spore ornamentation, please.

            Not really fucusing up and down gives a rough idea and spiral thickening is easy to see, there might be another way with fancier light microscopy to see these more clearly, say with top lighting, but difficult at this scale. I woud be interested in any ideas!

            Neil

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