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.
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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.
First for a couple of well known and uncontroversial lichens, both Caloplaca (despite appearances). C. flavescens and C. teicholyta.
Caloplaca flavescens again, beside the lemon yellow Candelariella medians.
Caloplaca dichroa, living up to its name with orange and yellow individuals. Described as new to science in 2006 (despite being the common blastidiate Caloplaca on tops of limestone memorials across the country, and having distinctive spores).
What about this dark scurfy crust with minute black apothecia. I had a hunch in the field but had to examine microscopically to confirm Catillaria chalybeia (more common than generally realised on nutrient-enriched limestone).
A minute black perithecium (just above centre) sits at the edge of an area of bare stone, cleared of almost all lichens, algae and cyanobacteria. The clearing is caused by this strange fungus/lichen? Sarcopyrenia gibba (which has bizarre propeller shaped spores).
Verrucaria ochrostoma, a lichen I revived from obscurity (left half) with grey superficial thallus, and V. hochstetteri (right half) with its thallus immersed in the stone.
Verrucaria hochstetteri (lower half, immersed thallus + perithecia). Upper half has a similar lichen (looks like the stone has woodworm) but with a raised 'lithocortex'. This could be one of several things in the field, microscopy proved it to be Polyblastia albida.
Lecanora horiza (upper half) with L. campestris (heavily chewed) below. These two lichens were not distinguished by churchyard recorders until after my work with Jiri Malicek in 2013.
Here is one of the large, richly muriform Polyblastia albida spores. Difficult to see the septation in fresh material but a few moments heating over a tea light candle flame quickly 'cleared' the spore.
Catillaria chalybeia in section. Some individuals lack the dark green pigment and then they may be confused with the var. chloropoliza which is a different sort of thing occurring in more specialised habitat.
During my early microscope investigations, I noticed two features of C. chalybeia not mentioned in the books. The rounded hyphae of the hypothecium are somewhat distinctive. At the time I first saw the pale patches on the photobiont cells, I had no idea they were haustoria.
The Lecanora albescens has familiar but mysterious 'Ribena' spots. For the first time ever I found a possible culprit as I will illustrate in the next tweet.
First the pigmentation in section, colourful, slightly dulls but mainly unchanged in K.
After staining I found strange clusters of minute cells (little over 1 micron) probably arising from hyphae ascending from the lichen tissue. Have I seen the first glimpse of whatever it is that causes purple spots on Lecanora albescens?
A distinctive basal zone is much more a feature of sandstone gravestones but the base of this limestone one has Caloplaca citrina, Opegrapha ochrocheila and Verrucaria elaeina, not found anywhere else (this zone often neglected during churchyard surveys).
There is one taxon on the stone that I think is still much misunderstood (Verrucaria nigrescens f. tectorum). We seem to lump at least two separate entities under this name.
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.
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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.
With experience, L. lichenicola can sometimes be recorded on sight in the field but a certain amount of caution is advised.
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.
The specific epithet relates to the curved ascospores.
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.
Can anyone find L. antiqua on relatively modern stonework?
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).
Here we have the two British Flavoparmelia species side by side. Similar colour. F. caperata (left) tends to be more robust, soredia coarser, produced in pustular soralia. If in doubt a simple chemical test will distinguish them.
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.
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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.
The soralia of Ramalina farinacea are usually neatly oval in shape and restricted to edges of branches. The soralia of Evernia are irregular in shape and are not restricted to edges of branches.