Diploicia canescens

1. Caloplaca saxicola

No. 2:
Infertile crust which is placodioid-lobate
Sorediate
K+ yellow
No isidia
C-

This one was quite easy and it ran through the key OK to this species with the above information. One that quickly becomes recognised by beginners.

Diploicia canescens

Caloplaca saxicola

I'm attempting to identify and list all the lichens in a local churchyard as a project to help me become more confident in identifying species in this group. This one is the first:

Pre microscopic clues:

Thallus yellow, crustose and lobed

Apothecia yellow, lecanorine and up to 1mm.

Apothecia K+ magenta

The above K+ magenta reaction suggests that the Lichen is Caloplaca or Protoblastenia.

Hymenium 100µm

Ascus 57x12µm

Spores 10x6µm and polaricular

Spores are colourless and simple with Protoblastenia which leaves us with just Caloplaca:

Thallus corticate (having a cortex)

On Rock

Cortex yellow K+ purple

Placodioid-lobate

Lobes less than 2mm, Ascospores ellipse shaped

Marginal lobes 2-5 times longer than wide with no blackening

Lobes 1mm or more

Lobes yellow with some white pruina, bloated, about 2x longer than wide on calcareous rock

Caloplaca saxicola

Caloplaca saxicola apothecia section

Caloplaca saxicola ascospore

Usnea subfloridana

Found about 10ft up on a tree trunk in the Forest of Dean this lichen took a bit of work to get a sample for identification:

Holdfast area blackened indicating it is either: U.flavocardia, U.fragilescens, U.subfloridana, U.silesiaca or U.wasmuthii.
Medula section is Compact not Lax ruling out U.flavocardia and U.fragilescens
This leaves us with three remaining Usnea's: subfloridana, silesiaca and wasmuthii. These three are difficult to separate in the infertile state. Had it been fertile then subfloridana would have been the favourite. As it is, the differences are down to the annual rings in the darkened holdfast. wasmuthii has regular annual rings whereas subfloridana has irregular. Wasmuthii is said to have a brickwork like pattern. Taking into account this pattern and the status and distribution we are left with Usnea subfloridana.

Usnea subfloridana

Usnea subfloridana isidiomorphs

Usnea subfloridana stem section

Physcia tribacia

When found on site it was suggested that this lichen was Physcia tribacia. I collected a sample and had a go at keying it out:
Getting to Physcia was achieved by the following characters:
Foliose lichen
Photobiont which is chlorococcoid (trebouxioid) and not cyanobacterial.
Lobes that are spreading rather than strap shaped and not hollow
Lobes lacking tomentum on the lower surface (felt like mat of fungal filament known as hyphae).
Whitish to pale grey coloured lobes with paler under surface, K+ yellow cortex, pseudoparenchymatous upper cortex (cell like structure formed by hyphae fusing together)

Getting to species level:
Lobes lacking marginal cilia (eliminating tenella and adscendens)
Soredia (fungal hyphae wrapped around a photobiont cell) developing on the underside of the lobe tips.
Lower cortex also pseudoparenchymatous.

Probable Physcia tribacia

Thallus section of probable Physcia tribacia

Toninia aromatica

I spent some time with this one and a had difficulty coming to a satisfactory conclusion. All the clues were giving me several options none of which seemed right at first but a photo of a Toninia following a saxicolous crack got me finally to the right group. Other groups considered were Catillaria, Cliostomum and Lecania. The reaction of K+ y put Cliostomum in the picture but it turned out to be a red herring. The spores are 17µm long and 3-septate. The paraphyses are with a swollen apex with pigmented tip.

Toninia aromatica

Rinodina bischoffii

A lichen that looks on first inspection to be lecanorine but the apothecia section shows it to be lecideine. The 16x11µm spores are quite distinctive so getting to Rinodina was quite easy.

Rinodina bischoffii

Rinodina bischoffii spores

Oxyrrhynchium hians

Oxyrrhynchium hians is a common pleurocarp which can be identified quite readily with care and a good hand lens in the field. With the example below I could see through the hand lens the nerve extending past the half way mark but not reaching the tip and the margin of the leaf toothed. A good feature for O.hians is the leaves being spaced out along the stem.

Oxyrrhynchium hians leaf

Oxyrrhynchium hians