Lichen mosaics seem like confusing puzzles to beginners. Once you can recognise basic growth forms such as placodioid, they can be broken down into manageable groups. This list is relevant to churchyards across much of lowland England.
Thread Caloplaca flavescens vs. C. aurantia

https://twitter.com/obfuscans3/status/957551950060572672

A thread about the lichenicolous fungus Laetisaria lichenicola, including the surprising way it was added to the British list in 2015 and hints about identifying/recording it. New British species aren't always discovered by the established experts.

Micarea curvata is a very inconspicuous lichen. I had the privilege of being present when the first English occurrence was found, in the company of Brian Coppins who originally described the species. Although the 'Flora' gives the habitat of Micarea curvata, more detailed guidance would help people to locate colonies of it in lowland churchyards.

I have a lot of anecdotal information about various lichens, along with copious notes from my own observations. This thread is about Lecanora antiqua, described as new to science by Jack Laundon in 2010. Ivan Pedley suspected two taxa were involved, a suggestion I still find somewhat persuasive. Jack Laundon didn't mention this possibility when he described L. antiqua.

A few more parmelioids (Parmelia and related genera) from my walk today.
Can you detect the yellowish tinge in this Flavoparmelia caperata (pure grey Hypotrachyna at top right for comparison). Flavoparmelia caperata in lower half, Hypotrachyna revoluta above. Again the subtle difference in colour which can only be accurately judged when the lichens are dry (they all become greener and rather similar in colour when damp/wet).

When dealing with mature specimens, Ramalina farinacea (left) can usually be readily distinguished from Evernia prunastri (right) and learning to separate them is a good exercise for beginners and improvers.
Thread. Evernia has a slightly matt texture (perhaps like fine tissue) whereas Ramalina is more cartilaginous (as if moulded in plastic). The undersides of Evernia branches are usually starkly different (white) to the upper side. In Ramalina underside similar or only slightly paler.

Today's gravestone, Joseph Tomlin, d. 1855, oolitic limestone. 'Only' 18 lichens plus one LF, but something a bit different, mossy and with a taxonomic conundrum.
Thread. Four lichens grew upon bryophytes on this stone: Agonimia, Bilimbia, Diploschistes and Lepraria lobificans. The first two in particular are usually found on moss.
The Weddellomyces was parasitic on Caloplaca flavescens.

I have been sent a very interesting query from a correspondent who found this lichen on a fragment of ironstone lying on the ground. This thread will illustrate the value of recording what you observe, even if you can't name the lichen. My correspondent assigned a provisional genus - Lecania. I think it belongs in a different genus but it is useful to make an initial hypothesis and then to keep an open mind.

Today's gravestones, a headstone and a footstone, both limestone, Eliz. Packwood, 1917. A couple of dozen species, one of which a lichenicolous fungus.
Thread: Plus Verrucaria polysticta on the footstone. 10/24 are members of the Verrucariaceae. C. dichroa described as new in 2006. V. obfuscans added to British list in 2015.

We tend to record Diploscistes muscorum when parasitic on Cladonia (as here, from dorsetnature.co.uk/pages-lichen/l…) and D. scruposus when growing directly on rock. There are supposed to be microscopic differences but my observations seem difficult to resolve with the literature.
Thread: Today I came across a colony growing on moss, no Cladonia in sight, on a gravestone. The number of spores per ascus fits muscorum while the septation of the spores fits scruposus! This not the first time I have noticed this problem.

Catillaria nigroclavata is familiar to me these days on twigs and branches in my region. Will I learn any more about it if I attempt to make some drawings of it? At first sighting, C. nigroclavata (in lower part of image) is very similar to Amandinea punctata (above). With careful study differences in appearance of both thallus and apothecia become apparent.

When sectioning fruiting bodies which are immersed in stone, the fine edge of the blade is soon blunted. How do I cut numerous sections of saxicolous material while minimising waste of razor blades?
Thread

https://twitter.com/obfuscans3/status/1487904835877883906

There are two basic types, single edged above which are safer and more robust but without the ultra-fine edge that I prefer in the double edged type below.

West and East facing sides of the limestone gravestone to Mercy Ann Smith, died 1911. The latest stone to be scrutinised in detail. 24 lichen spp. present, over a third of which would have been unrecognised or likely misinterpreted at the start of this century.
Thread 7/24 are members of the Verrucariaceae, a generally poorly understood and misinterpreted family. Caloplaca dichroa was described as new to science in 2006. V. elaeina and V. ochrostoma were lost to the consciousness of most lichenologists until into the present century.

A thread with a few grey 'parmelioids' from my walk today.
Punctelia subrudecta (left), Parmelia sulcata (right) Hypotrachyna revoluta (left) with erect lobes, the apices covered in fine soredia.
Parmelia sulcata (right) with angular lobes and white tipped ridges.

In the field I thought this was a potential candidate for Bacidia phacodes, which would only be the second record for my parish. It turned out to be something more mundane. Any guesses? (Apothecia up to c. 0.5 mm diam.)
Thread. The spores are 3-septate and fusiform so this is not B. phacodes. In fact it is Lecania naegelii with apothecia lacking pigment (the fruits can vary from white to black with various shades in between in L. naegelii).

Another new lichen for my parish today (after 15 years studying my patch, I continue to add species and stack up mysteries). A young colonist on smooth hazel stem. Perhaps just Lecidella elaeochroma was my thought in the field but best check... A glance at a section under low power suggests it is not L. elaeochroma, there is a purplish tinge to the pigments, no obvious bright aeruginose and the exicipular pigment doesn't go all the way under the hypothecium.

Pyrrhospora quernea, a nice image showing the granular-sorediate thallus, dark brown apothecia and dark boundary lines. How do my observations compare with the literature?
Thread
Image from stridvall.se/lichens/galler… LGBI2 states that the thallus is "Thick, granular sorediate, granules to c. 0.15 mm diam." Altho' some are that big, it gives a misleading impression. My measurements are (30-)50-70(90-150) microns, the majority less than half the diam. of the maximum size.