Orcularia insperata?

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petemartin
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Joined: Mon Nov 25, 2019 1:11 pm

Orcularia insperata?

Post by petemartin »

I brought home a sycamore twig from Grizedale Forest in Westmorland last week- and sectioned some small black apothecia (maybe 0.3mm diameter) expecting them to be Catillaria nigroclavata, though they didn't look quite right.
I was somewhat surprised to find that the spores were brown, sometimes somewhat "lemon shaped" and sometimes obviously polarilocular. In size, they are about 11.5- 16um x 7.5-8um.
The jizz ( and spores) were wrong for Rinodina sophodes... but after a bit of head scratching Orcularia insperata looks possible. That's well out of my geographic comfort zone though.
What do people think? If it is, it takes the distribution map north considerably...

Many thanks

Pete
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JennyS
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Re: Orcularia insperata?

Post by JennyS »

Yes, looks good for Orcularia insperata (Rinodina biloculata).
I seem to come across it quite often on small twigs in Dorset the last couple of years but not sure whether that's because its on the increase or just that I'm getting better at spotting it!
Jenny Seawright
Mark Powell
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Re: Orcularia insperata?

Post by Mark Powell »

If I found Pete's lichen in my region I would certainly record it as Orcularia insperata (Rinodina biloculata). It seems to be a recent arrival (this decade) in my region, or at least previously must have been so rare that I didn't pick it up at all. One could suggest that I just hadn't noticed it before and that I suddenly got my eye in for it but I did manage to find it occasionally in the 2010s when I visited counties such as Wiltshire. I never record it in the field. There is a large area of young hawthorn scrub near me and this site is useful for monitoring colonists. I can now find O. insperata fairly easily on hawthorn twigs there, as though it has already become a part of the twig community and not just rare one-offs. At the scrub site, three look-alikes grow on twigs, Amandinea punctata, Catillaria nigroclavata and Orcularia insperata. The Catillaria usually has a darker, thinner thallus and apothecia with little or no tendency to become convex. The Amandinea and Orcularia are very similar to each other with pale grey thallus, sometimes visibly comprising tiny warts, and apothecia which tend to become gently convex on maturity. Candidates for O. insperata have a dark brown rather than black margin. As an experiment, I collected about 15 specimens of these and labelled them provisionally in the field. Microscopy showed that I was right more often than not but my field identifications of all three species were not entirely reliable.

It is important to clear ascospores of fresh material (heating a slide of a water mount, for example some way above a tea-light candle flame works fine if you don't use strong K or N). Pete's micrographs show cleared spores. In addition to the pleasingly distinctive lemon shape of the spore as a whole, the spore wall is thin at the apices, and greatly thickened in the centre to form a broad septum.
Attachments
Orcularia insperata, this specimen from a wind-blown Fraxinus branch, Bedfordshire. Ignore the arrow, everything inside the red ring is O. insperata.
Orcularia insperata, this specimen from a wind-blown Fraxinus branch, Bedfordshire. Ignore the arrow, everything inside the red ring is O. insperata.
Ascospores still within ascus, mounted in water without heating.
Ascospores still within ascus, mounted in water without heating.
FIriwfqXwAErVn0.png (363.55 KiB) Viewed 46 times
Ascospores after heating.
Ascospores after heating.
FIrizC8XoAcQNlN.png (408.54 KiB) Viewed 46 times
Ascospores thin-walled at apices, greatly thickened in the centre to form a broad septum.
Ascospores thin-walled at apices, greatly thickened in the centre to form a broad septum.
More O. insperata ascospores.
More O. insperata ascospores.
FIrke7fXwAIgBB0.png (682.01 KiB) Viewed 46 times
petemartin
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Re: Orcularia insperata?

Post by petemartin »

Thank you very much for this. That takes the map of O. insperata into a whole different region (I wonder how it arrived at a Forestry Commission site?). I've now found C. nigroclavata sufficiently often enough for me to almost be confident enough to record it on sight (A. punctata I find quite rarely around here). This will make me much more cautious, though the Orcularia had more of a warty thallus and doesn't appear to have the sooty darkness or black margins of the Catillaria. Many thanks again.
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