What is your favorite Crustose Lichen observation?

I know many of you might be looking at the topic chive weirdly so let me explain! I have
been on vacation to NM for a bit and started seeing all these crustose lichens all over the place so I tried to think about wha t my favorite was! Spoiler: it was this completely unassuming lichen: https://www.inaturalist.org/observations/145195092
I started to wonder after deciding what other peoples faves from their observations of these lichens are… so here this is!
Aka: https://www.inaturalist.org/people/sageost


Welcome to New Mexico. I particularly enjoy bright yellow lichens on granite boulders.

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CV ided not the one in centre of your observation btw, it’s not looking like Physcia (it is present on the photo).
I like those that don’t get any ids, at least think more about them:

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My favorite is also my most recent: Genus Xanthomendoza (I think). So tiny, you’d easily overlook it, but zooming in revealed wondrous details.

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I love the really showy yellow ones. (Also good you limited it to crustose since I also like beard lichens giving me that feeling of an ancient forest and cladonias giving me that feeling of being in a fairy world…)

I picked four species, all seen in the past two weeks. The first two are really common in cities here - they grow on both walls and park trees, and fairly new ones at that. Clearly they are pollution resistant, fast growing and have no substrate specificity, so not very typical for a lot of lichen. The last two I’ve see much less often, and only on walls. The third one was giant, probably 10 cm across. The fourth one was tiny, only maybe 1 cm across.

Crustose Lichens are among my favourite organisms and I really love them.
Unfortunately my camera broke some time ago and I haven’t been able to replace it yet. The last few years have been just horrible and haven’t gotten me any further. I really hope that I will be able to document beautiful and rare lichens for iNaturalist again soon.

Here are some of my own observations from Germany that I really like:

Calogaya spec.: https://www.inaturalist.org/observations/74862222
Candelariella medians: https://www.inaturalist.org/observations/74663750
Diploschistes scruposus: https://www.inaturalist.org/observations/49247842
Graphidaceae spec.: https://www.inaturalist.org/observations/76636645
Lecidea spec.: https://www.inaturalist.org/observations/50679013
Rhizocarpon alpicola: https://www.inaturalist.org/observations/49070435
Rhizocarpon lecanorinum: https://www.inaturalist.org/observations/49076885
Teloschistaceae: https://www.inaturalist.org/observations/51852720
Variospora flavescens: https://www.inaturalist.org/observations/52616422
Xanthomendoza borealis: https://www.inaturalist.org/observations/52273535
Xanthoparmelia conspersa: https://www.inaturalist.org/observations/47346000
Xanthoparmelia spec.: https://www.inaturalist.org/observations/74665955

Of course there are so many more beautiful and interesting crustose lichen species from all around the world…

Graphidaceae, French Guiana: https://www.inaturalist.org/observations/144123180
Lecanoromycetes spec., Antarctica: https://www.inaturalist.org/observations/37208056

Here is the amazing genus Stellarangia from the Namib Desert and a similar looking lichen from the Atacama Desert in Chile:

Stellarangia elegantissima: https://www.inaturalist.org/observations/18882566

Teloschistaceae spec., Atacama: https://www.inaturalist.org/observations/75681785, https://www.inaturalist.org/observations/97097321

It always hurts me when people destroy lichens with high-pressure cleaners or other means, they are wonderful organisms.

Of course, the entire variety of lichen species is even more colorful and richer in form than just the species that are called crustose lichens, but oh well, there would certainly be hundreds more species worth mentioning.


I’m very fond of Smokey-eyed Boulder Lichen, Porpidia albocaerulescens, partly just because I like the common name and partly because it’s one of the very few lichens I can identify! Here’s one of my observations of it: https://www.inaturalist.org/observations/118441702


I love this one, it looks similar to my third one but has those nice orange apothecia. Wonder if it grows around here - I’ll be looking for it for now!

Yeah, whenever I see some old city wall or cemetery or church wall and it’s spotless clean I’m “no, what misguided person destroyed all the lichen and mosses and ferns that would love growing there and make it a beautiful instead of ugly wall”

I think picking favourites is really hard, especially on looks, but I can think of two this year that stand out, very much not on looks but on circumstances, both leaning heavily on the joy of discovery but in quite different ways:

Buellia disciformis
I fount this one growing on a beech in Høstemark Skov, a forest reserve that usually has fairly restricted access but that I was allowed to visit as part of a BioBlitz. It was near the end of the day in an area that didn’t seemed less rich and somewhat more disturbed than some other parts I had seen when I saw several thalli of what I initially assumed was a somewhat aberrant Lecidella elaeochroma but a shine with the UV torch quickly showed it wasn’t. I scraped off a tiny piece and was quite surprised back home at the microscope to find it was the first Danish record in 15 years of a species considered very rare here (even though it is rather more common in some nearby countries). The reserve has been surveyed quite intensely in the past so I had assumed ahead of time that amateur me wouldn’t be able to find anything new! (I added a couple other species to the reserve list as well even, including another local rarity Lecanora intumescens). I upload most of my stuff to a local site rather than iNat (where I mostly ID things), this one included, so it isn’t on iNat but here are some pictures:
Overview: https://svampe.databasen.org/uploads/2022-10284207_BylSNbW1i.JPG
Apothecial section (rather poor picture): https://svampe.databasen.org/uploads/2022-10284207_BygxSNbWkj.JPG

Lecidea nylanderi
I had for a while been noticing a weird crust in my local forest that was somewhat Lepraria-like but with a distinct prothallus but attemtps at keying it out didn’t really go very well. That was until I noticed an observation rather like it by Jurga when browsing Identify, asked about it, and got the encouraging answer that it should be a fairly distinct species without too many concerning lookalikes, and after a bit of back and forth including a specimen with odd chemical reactions (possibly because of overgrowing actual Lepraria) I made an observation that everyone (including on the local observation platform) was convinced was a good L. nylanderi. It seems the species has been very overlooked here, my first confirmed one was only the second in the country. I have since then grown more comfortable with it and it is quite numerous several places in my local forest and in several other places I visited I have found it quite quickly when looking in similar habitats.
All the iNat observations involved in this story:


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