Observation 89097: Verrucaria muralis Ach.


Proposed Names

61% (2)
Recognized by sight
31% (2)
Recognized by sight

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= Observer’s choice
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Yeah, let’s stick with Verrucaria, then
By: Jason Hollinger (jason)
2012-12-16 08:28:05 HST (-1000)

Obviously J. Bennett wasn’t convinced, either! :)

I’m not a specialist,
By: Andrew Khitsun (Andrew)
2012-12-16 08:20:40 HST (-1000)

but I have doubts about A.conoidea. It does seem to look slightly different macroscopically, from whatever images one can scrounge online. But Thomson also says it’s supposed to grow on shaded limestone in moist areas. This is on sandstone, even though sandstones around here are calcareous, due to the leaching of limestone caps. But this one grows in pretty exposed areas – partial shade at best.

Thanks again, Andrew
By: Jason Hollinger (jason)
2012-12-16 07:53:26 HST (-1000)

I never even considered Acrocordia. It’s in the British Flora, I’m still trying to figure out what distinguishes it from Verrucaria in general… Tricky. I found spores > 20µm, so even if they really were immature and later would develop septae, they would still be significantly too large for A. conoidea. And it’s involucrellum should diverge from the exciple toward the base, not adhere. I still lean toward Verrucaria, but I’m still new to this group! Macroscopically the two species look pretty similar.

Tentative ID from UW-Madison
By: Andrew Khitsun (Andrew)
2012-12-16 07:29:11 HST (-1000)

Here are the comments on the envelope (the ID of Acrocordia conoidea was with a question mark):
Perithecia – ostiole, not clearly papillate .2-.5 mm
Spores – immature, no septa, not clearly uniseriate (?-can’t read that last word)
Photobiont Gloeocapsa? – not clearly Trentepohlia

Microscopic details
By: Jason Hollinger (jason)
2012-03-12 14:48:18 HST (-1000)

Perithecia with black excipulum completely surrounding it, but hard to distinguish above from the thicker, browner, appressed involucrellum. Green algae just below the involucrellum in a tiny collar around the base of the perithecia (immersed). Hymenium was I+ fleeting blue turning immediately greenish then deep red-brown. Spores 8 per ascus, ellipsoid-oblong, simple, hyaline, textured?, ~20×10µm.

Jason, this is #8312011-12
By: Andrew Khitsun (Andrew)
2012-03-11 04:51:22 HST (-1000)

It’s pretty common on sandstones here, usually on exposed ledges, could be partially shaded. I confused this one with another species in the past, like in observation 89098, or observation 89099, just because they all look like tiny dots scattered around sandstone ledges in the field. Having taken the photographs, I can see that they’re quite different in size and other features.