Phacographa zwackhii

Post Reply
peterbisset
User
Posts: 19
Joined: Wed Jun 28, 2023 8:59 am

Phacographa zwackhii

Post by peterbisset »

Phlyctis argena on an ash at NY7220 near Appleby Cumbria showed dark brown irregular spots with possibly darker margins apparently growing through and on the thallus. These peeled off easily and did not penetrate deep into the thallus they proved to be apothecia, asci 8 spored, not long and thin 2-3 ranks of spores inside, the spores are Opegrapha-like, club shaped and 3-septate size 19x6 mu to the best of my measuring ability with this equipment.

looking at LGBI3 and the internet I wonder if this is Phacographa zwackhii.

Microscope photo snapped with my mobile down the eyepiece of an old Prior brass microscope I keep in Appleby for just such occasions. Should be able to get some better images once I'm at home again.
P4120003.JPG
P4120005.JPG
P4120003_cr.jpg
IMG_20240412_194156464~2.jpg
x400 scale 3.12 mu divisions
x400 scale 3.12 mu divisions
IMG_20240412_195902561 (1)_cr.jpg (136.14 KiB) Viewed 149 times
Neil Sanderson
Frequent user
Posts: 444
Joined: Tue Jan 08, 2019 7:30 am

Re: Phacographa zwackhii

Post by Neil Sanderson »

Peter

The bottom two pictures show certainly Phacographa zwackhii, but much of the black flecks in the thallus pictures look like the black sterile irregular flakes of unknown nature that are quite common on Phlyctis argena. I have never found any structure in these, but admittedly have stopped looking quite sometime ago. Phacographa zwackhii has regular round apothecia with a very rough disk. Photo here https://italic.units.it/index.php?proce ... e&num=2661 and micrographs of an apothecia cross section and spores here https://www.researchgate.net/publicatio ... ileContent.

Either the irregular black flakes are Phacographa zwackhii and I had got that wrong, or there was an actual Phacographa zwackhii apothecia among the mystery black flakes.

All the best

Neil
Neil Sanderson
peterbisset
User
Posts: 19
Joined: Wed Jun 28, 2023 8:59 am

Re: Phacographa zwackhii

Post by peterbisset »

Thanks, I deliberately dissected a nice round looking one from my sample so obviously got lucky! I'll have a look at a fleck to see what I can find.
peterbisset
User
Posts: 19
Joined: Wed Jun 28, 2023 8:59 am

Re: Phacographa zwackhii

Post by peterbisset »

A frustrating afternoon, lucky it was raining outside. It took me 3 hours to find another fertile sample. I'm not convinced that it is all not P. zwackhii as the unstructured pigmented material, hyphae and odd photobiont cells look much the same as when there is a hymenium. If I hadn't chosen the right sample the first time I would have given up looking long before finding anything. I will certainly only be collecting the biggest roundest and deepset spots next time.
Neil Sanderson
Frequent user
Posts: 444
Joined: Tue Jan 08, 2019 7:30 am

Re: Phacographa zwackhii

Post by Neil Sanderson »

Peter

OK, interesting I will have another look at the black stuff. At the least it could be hidding apothecia of Phacographa zwackhii. All my Phacographa zwackhii finds were on clean Phlyctis argena thalli.
Neil Sanderson
Post Reply