Wednesday, 7 October 2015

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

Tuesday, 6 October 2015

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
K+ yellow
No isidia

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
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

Monday, 5 October 2015

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