Rhizocarpon lavatum?

It doesn't take much effort to determine a Rhizocarpon but getting to species level is a lot more difficult. This one wouldn't key out so I instead went with the closest match. No idea what the difference between muriform, submuriform and eumuriform is and no explanation in the book. Perhaps it would have been easier to reach an ID had I have known. I've put the details here to come back in time and re-evaluate:

Spores: muriform (or could be submuriform or eumuriform) 25x11.25µm turning brown when mature.
Ascus: 120µm
hypothecium: brown
hymenium: colourless
epithecium: brown
apothecia: 0.8mm
habitat: siliceous rocks near stream

Pos Rhizocarpon lavatum

Caloplaca from Brecon Beacons 25th March

Found on 25th March 2016 on a gate post this Caloplaca was not found to be identifiable with my level of expertise currently. A shortlist was drawn up using apothecia size (1mm) and habitat giving Caloplaca citrina as the best guess. Both the thallus and apothecia are K+ purple eliminating C. virescens and C.cerina. Apothecia colour elimnated herbidella. There were few polaricula spores the largest measured 15x4.5µm. Some of the paraphyses had swollen tips measuring 3.75µm

Lecanora pulicaris

Lecanorine apothecia up to 1mm
Thallus white crustose K+ yellow
Spores 15x7µm simple
Fine crystals extending from the epithecium into the hymenium seen with a polarizing filter.
Massive crystals in the exciple.

Lecanora pulicaris

Opegrapha sp. (vulgata)?

I've had to put this lichen down as Opegrapha sp. as it doesn't key out. I've put the information here so it can be referenced in the future should I get more information regarding missing species in current literature. Closest match would be O.vulgata but what looks like pycnidia is in fact the early stages of new lirellate.

Lirellate 1mm
Thallus endolithic with a greenish tint
No pycnidia, only newly formed lirellate resembling pycnidia.

Spores 5-septate 22x5µm
Ascus 42x12µm

Generic Key 5 p.57
True exciple present
Ascospore septate
Ascospore multiseptate
Ascospore lumina cuboid
Ascospore colourless
Lateral exciple in section brown-black
= Opegrapha or Lecanographa

Opegrapha key:
Photobiont present (not lichenicolous)
Thallus without soredia, apothecia present
Ascospore 5-septate
Apothecia disc remaining slit like
Ascospore 4-7 septate
On bark
Ascospore 4-9µm wide
Key end, no match.

Opegrapha's characteristics:
O.anomea - On Pertusaria amara
O.areniseda - Mainly coastal on soil and sand
O.atra - Clearly defined mosaic forming patches
O.brevis - On Thelotrema petractoides
O.calcarea - On rock
O.cesareensis - Coastal siliceous rocks
O.corticola - Sterile
O.demutata - White pruina
O.dolomitica - On calcareous schists
O.fumosa - Sterile
O.glaucomaria - On Lecanora rupicola
O.gyrocarpa - On siliceous rock
O.herbarum - Slit opening wide when mature
O.mougeotii - Limestone, mortar, calcareous sandstone
O.multipuncta - On small branches
O.niveoatra - Often sterile
O.ochrocheila - K+ magenta-red
O.parastica - On Aspicilia calcarea
O.paraxanthodes - Mainly upland deeply shaded rocks
O.pertusariicola - On Pertusaria leioplaca
O.physciaria - On Xanthoria parietina
O.prosodea - 50-70µm ascospores
O.pulvinata - On Dermatocarpon miniatum
O.rotunda - On Physconia distorta
O.rufescens - Apothecia .3 to .5mm
O.rupestris - On V.baldensis
O.saxigena - Deeply shaded siliceous rock
O.sorediifera - Sterile
O.sphaerophoricola - On Sphaerophorus globosus
O.subelevata - On limestone, mortar and sandstone
O.thelotrematis - On Thelotrema lepadinum
O.trochodes - Apothecia 0.15-0.4mm
O.varia -
O.vermicellifera - Similar to Lecanactis subabietina
O.viridis -
O.vulgata -
O.xerica -
O.zonata - Shaded siliceous rocks
O.zwackhii - On Phlyctis argena

Caloplaca citrina

1. Caloplaca saxicola
2. Diploicia canescens

No. 3
Thallus crustose-areolate
On basic rock
Thallus K+ purple

Again the K+ purple led to a Caloplaca species:

Thallus entirely sorediate
Thallus without any definite shape or form to the margins (see C.xantholyta)
Thallus yellow-green with distinct areoles often sparsely fertile

Caloplaca citrina

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