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Possible Opegrapha areniseda

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  • September 3, 2025 at 7:35 pm #33075
    SylviaD
    Participant

      Hi,

      I think that this is Opegrapha areniseda, with its numerous pycnidia, many in groups. I wondered if it was possible to confirm this from the photos attached. The lichen was found on the mortar on the north face of a flint and mortar church wall in Laughton, north of Eastbourne in Sussex – nestled among a profusion of Opegrapha calcarea. All chemical tests were negative. The pycnidia are in the range 0.1-0.3 mm and the conidia are bacilliform measuring 3-5 X 1-1.5 um. There are a couple of records for this lichen not that far away from 2003.

      Thank you,

      Sylvia

      September 4, 2025 at 9:44 am #46664
      Paul Cannon
      Participant

        I’m not sure this is right – the thallus of O. areniseda is quite distinctive (see image). If these aren’t pycnidia of Arthonia (Opegrapha) calcarea agg., possibly you have O. hochstetteri (which is a parasite of Verrucaria hochstetteri). Both have similarly sized conidia to your specimen.

        Life is never simple…

        Paul

        A06617a.jpg

        [attachment=0]A06617a.jpg[/attachment]

        September 4, 2025 at 6:43 pm #46665
        SylviaD
        Participant

          Thanks for the information Paul – wishful thinking on my part there.

          Sylvia

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