Stigmidium arthoniae?

This topic is empty.

Viewing 3 posts - 1 through 3 (of 3 total)

Author

Posts
August 10, 2024 at 10:49 am #32853
JennyS
SW Ireland, tiny perithecia on the thallus of Arthonia radiata.

I initially thought Stigmidium arthoniae but the spores were only in the region of 12 x 3 µm,which is considerably smaller than the size given in the 2010 draft keys (17-23 x 4-5 µm, 1(-3) septate).

Comments and suggestions appreciated!

~~[attachment=4]~~w Stigmidium arthoniae Q 240719 011.jpg[/attachment]

~~[attachment=3]~~w Stigmidium arthoniae Q 240719-2.jpg[/attachment]

~~[attachment=2]~~w Stigmidium arthoniae Q 240719-4.jpg[/attachment]

~~[attachment=1]~~w Stigmidium arthoniae Q 240719-7b.jpg[/attachment]

~~[attachment=0]~~w Stigmidium arthoniae Q 240719-8.jpg[/attachment]
August 10, 2024 at 5:24 pm #46147
Paul Cannon
Participant
It certainly looks like a Stigmidium, though all those dark hyphae in your micrographs makes me wonder whether it is a Sphaerellothecium (these have a superficial mycelial network, though that could be inconspicuous). But I can’t find any species of either genus associated with Arthonia with similar spore dimensions, so I suspect it is probably undescribed.

Best wishes

Paul
August 10, 2024 at 9:18 pm #46148
JennyS
Thank Paul, I was starting to suspect ‘undescribed’ might be the case as there was nothing with similar sized spores mentioned in any of the LGBI3 Arthonia descriptions.

Despite investigating every possible black dot on Arthonia radiata thallii on that twig other than host pycnidia (which seem to be fairly frequent) there was nothing further.

I’ll be there again in a couple weeks time and will bring more twigs back with me to check!
Author

Posts

Viewing 3 posts - 1 through 3 (of 3 total)

You must be logged in to reply to this topic.