[Mark Powell]

Sorry to be lazy and answer this with a link:

https://twitter.com/obfuscans3/status/1217429868499099649

As you will see, in my opinion LGBI2 is rather misleading about the rhizines of P. grisea. They can be considerably darker and also quite considerably ‘frayed’ (even branched) than is stated and illustrated in the ‘Flora’. For about a year I wondered if there was another taxon involved, or whether P. enteroxantha sometimes lacked K+ yellow pigment but eventually I concluded that the rhizines of P. grisea are not as pale and simple as generally stated.

[Mark Powell]

I have just dug out my scans which I can attach here (you may still like to go and browse my twitter ).

The first (and so far only) formal publication of K/UV reactions was:

Powell, M. (2018) Spot tests and staining: some recent advances. Bull. Brit. Lichen Soc. 123: 77-82.

[The Winter 2018 edition of ‘The Bulletin’]

[Mark Powell]

When you click on my twitter link (previous post), you will need to scroll down the thread to see the scans of the Bulletin article detailing the K/UV reactions.

[Mark Powell]

I wrote a fair summary in the Bulletin and scans of this have been posted on my twitter:

https://twitter.com/obfuscans3/status/1207602169828069376

If you need further information, then do let me know.

So far, it is still the atranorin and confluentic acid tests that have proved potentially useful (though I suspect that there are others to be discovered).

The K/UV of atranorin is useful to confirm (or dismiss) low concentrations in e.g. Cladonia rangiformis and the medulla of Physcia aipolia.

[Mark Powell]

I wholeheartedly agree with the tone of Chris and Neil’s replies. If anyone has any genuine queries then we can all learn from having them posted on this forum. There are two aspects in particular that I like about airing queries in public. First is the way that so many others can learn from the discussion. Second is that it provides a sort of informal peer review. In the past, most determinations were an interaction between only two people. The forum is a very efficient means of sharing the identification process.

There will be instances where online determinations are not possible and a referee will have to handle the specimen. However, in most cases the determination can be discussed online which helps people to help themselves (much more so than a name scribbled on to a returned packet).

The best lichenologists are usually the most willing to accept that mistakes are made (and Neil is one of the very best). Sometimes a rush to help leads to insufficient consideration, other times an aberrant form throws us off guard, and we all have our weak spots. The collective wisdom of the community on a forum can often lead towards a satisfactory resolution.

Mark – thanks for performing the medullary reactions again and letting us know. I think we will provisionally consider your lichen to be a grey individual of Xanthoparmelia conspersa (fairly high probability). I am a strong advocate of examining things side by side and in this case, if you come across more typical X. conspersa, this could be used as comparison.

[Mark Powell]

It could be a chemical var. without usnic acid but perhaps more likely to be an individual in which the usnic acid colour is less apparent. Perhaps specimens growing in shade (or other environmental factors) leads to them having lower concentration of usnic acid. I have a nice specimen of X. tinctina which appears pure grey and some specimens of Hypotrachyna sinuosa are grey with little apparent hint of yellow-green.

One thing I noticed about your spot test is that you appear to have applied quite a drop of reagent. I prefer to apply reagents with e.g. the tip of a cocktail stick. If excess reagent is applied, one of several things might happen. The lichen substances might be dissolved and diluted to the point where they don’t react properly or substances from one structure (such as the medulla) may leach up into the cortex (or vice-versa) and give anomalous results. LGBI2 claims that the cortex of Parmelia sulcata is ‘K+ yellow>red’. This is presumably due observation of clumsy, profligate testing. The cortex of P. sulcata is K+ yellow and the incorrect stated reaction in the 2009 ‘Flora’ is probably due to salazinic acid from the medulla being flushed up into the cortex and reacting there. In addition, I have seen some good specimens ruined by great splodges of reagent.

Best wishes, Mark

The photograph shows the true spot reactions of Parmelia sulcata, performed carefully with the tip of a cocktail stick.

[Mark Powell]

I am going to throw another suggestion into the mix, not a definite identification at this stage. What about Xanthoparmelia conspersa? Although I would expect X. conspersa to be a yellow-green colour, that does depend on the specimen and the lighting. Mark, when viewed in daylight, does the thallus have any yellowish-green tinge or is it really pure grey? The morphological details seem to fit X. conspersa – the presence of isidia, the often numerous pycnidia, the lower surface mainly black with stubby rhizines. This suggestion would also explain the K reaction. I am not sure what to make of the supposed C reaction – I think we need a retry with that and carefully record what happens immediately on adding strong C to the exposed medulla.

If we decide that Xanthoparmelia is the right direction to go, then we also need a more careful K test just to rule out X. tinctina.

[Mark Powell]

I tried to key out Juliet’s lichen with the new Collemataceae key, assuming that we have decided that it doesn’t have any true ‘tomentum’ and arrived at couplet 40 where we are asked whether it is

a) On calcareous soil, brick or mortar

b) On rocks or amongst mosses on rocks

Scytinium turgidum and S. schraderi are keyed out by following the first part of the couplet, S. plicatile by following the second part and their presence isn’t duplicated on account of this couplet.

Juliet’s lichen was growing on a limestone wall so one would more likely chose the second option in the couplet but that leads to S. plicatile and not to S. turgidum.

An example of this problem of splitting on substratum at couplet 40 is that I have not infrequently found S. plicatile and S. turgidum both growing together on the tops of limestone chest tombs, same substratum but couplet 40 would require you to chose different substrata.

I apologise that I am finding problems with no intention of solving them as far as working on the keys is concerned. Personally I would ditch the dichotomous keys for families/genera altogether and instead provide tables of characters where they help and also separately work on multi-access keys. However, I feel certain that dichotomous keys will be provided and they will be a mixed blessing. They will lead to many incorrect identifications but at least they will be ‘something’. I am not trying to campaign against the inclusion of dichotomous keys, just expressing my considerable reservations about them.

[Mark Powell]

The draft definition of tomentum for LGBI3 has been slightly expanded and is currently as follows:

tomentum (-ose), felt-like mat of hyphae; a special case of pubescence in which the soft hairs are matted and usually pressed close to the surface.

For reference:

pubescent, having soft, short hairs (cf. tomentose).

I think the traditional use of ‘tomentose’ in ‘Leptogium‘ is rather unfortunate because e.g. the undersurface of L. burgessii has a mat of short hairs which are predominantly perpendicular to surface and so, in my opinion, the undersurface of L. burgessii (and L. saturninum) is more accurately described as pubescent.

If I am right, we are presented with a familiar problem. Do we stick with the terminology traditionally used for a genus and add notes to the glossary to explain how the normal meaning differs in certain genera, or do we change the traditional descriptions so they make more sense with a more standardised glossary. Neither way is particularly neat and we are stuck with finding solutions to the peculiarities that are the unfortunate legacies of authors working in different genera using terms in their own preferred ways.

An example of true tomentum, as defined by our current proposed definition would be seen on the upper surface of Peltigera membranacea. In that case the small hairs are predominantly horizontal to the surface and really do resemble felted material.

“It helps if you are familiar with the lichens included in the other couplet…” That is a perpetual problem. It is understandable that Juliet would be tempted to consider any hairs on either surface as significant, especially those short ones on the upper surface. In lichenology we are often expected to detect almost undetectable subtleties so when we notice a feature we assume that it is important enough to ‘count’. Looking again at the hairs on the upper surface of Juliet’s lichen, the hairs look mainly at the edges and I have managed to find a few instances of similar on Leptogium turdidum, very sparse and confined almost strictly to very close to the margins.

[Mark Powell]

Before I give my opinion on the identity, I am repeatedly disappointed by dichotomous keys. In my experience they are the cause of numerous misidentifications and misunderstandings. Whether they are a necessary evil, I’m not sure. For the moment they are the practical reality so we have to learn how to use them. I use dichotomous keys but always treat the ‘answer’ I arrive at with much scepticism and go on to a validation process. Many, many times I have failed to arrive at a convincing answer and it is only when I finally work it out by another means that I go back and work out what the compiler of the key intended.

My opinion of your lichen, not 100% certain but a very strong hunch, is that you have Scytinium turgidum. I will attach below one of the specimens I have examined while considering your query, not a great photo but gives an impression of the sort of thing and size of what I call S. turgidum.

Your first major problem arose at couplet 23 with the issue of tomentum. Many of the jelly lichens have pale rhizines beneath and I have seen them very well developed in species such as Blennothallia crispa. My specimens of Scytinium turgidum frequently have small white rhizines beneath. I haven’t managed to find much/anything in the way of hairs on the upper surface of my specimens but I can imagine any of them producing tiny sparse hairs.

Paul had the unenviable job of compiling the key to Collemataceae. I wouldn’t have wanted the job so my comments are not criticism. The key is a bit ‘cobbled’ together from the various keys in LGBI2. The tomentum issue is probably transferred from the old Leptogium key and in that key it was used to distinguish large foliose Leptogium species which are tomentose (such as L. saturninum) from large foliose species that are not distinctly tomentose. In that key, species such as ‘Leptogium‘ turgidum had already been keyed out before the couplet asking about tomentum.

The drawing on page 550 of LGBI2 has misled several people (including me initially) into thinking that L. turgidum must be L. schraderi due to be wrinkled. In fact, although L. schraderi is particularly wrinkled, I consider all members of the ‘plicatile group’ (turgidum, schraderi, plicatile) to be wrinkled when dry.

I am happy for my opinion to be challenged/contradicted but I have had the privilege of discussing this group in the field with Brian so hopefully I picked up some wisdom from him.

[Mark Powell]

I think that I have demonstrated Jack Laundon’s C+ reaction in the apothecia of Caloplaca albolutescens (probably identical in this sense to C. teicholyta which he mentions, and he may not have distinguished between them at that time). I will post the extract from Jack’s paper, then the apothecial margin of Caloplaca albolutescens in water, then in C and then in K.

[Mark Powell]

I agree with your quibble in the sense that it would be useful to know exactly what is going on and to describe the phenomenon accurately. Although I have presented my provisional results above, they still need checking further. Either an anthraquinone in Xanthoria parietina reacts red with hypochlorite or bleach IS contaminated with hydroxide and I have failed in my attempt to prove its absence.

My reason for advocating strong bleach results from early experience with the Churchyard Group when some people would fail to detect any C+ orange with Lecidella scabra (using value bleach). Ivan would come along with his gloopy Domestos and demonstrate that the same specimen was, indeed C+ orange. From then on, even if Domestos contained a bit of hydroxide contamination I was happy to use it for the strength of C reaction it gave.

I find that different individuals of Lecidella elaeochroma, even growing in the same mosaic-forming population, vary in their C+ orange reaction (and this can be seen very effectively by shining UV on to those mosaics where the ones that react strongly C+ orange give the strongest UV+ orange fluorescence).

On the subject of UV torches, the Convoy S2+ with Nichia 365nm chip is the one that is remarkably powerful and useful even in the field. Bear in mind that it uses 18650 type batteries (not commonly available in ordinary shops). I bought a couple of rechargeable ones with a charger.

[Mark Powell]

We should perhaps define the term ‘interascal filament’ in the glossary of the proposed LGBI3. An interascal filaments are any sterile hyphae that occur in between the asci. We are most familiar with paraphyses and periphyses but there are also pseudoparaphyses and others. For the ordinary observer, it may be difficult to decide whether one is looking at, for example, periphyses or pseudoparaphyses. Hence, in keys and elsewhere, the term ‘interascal filament’ is a nice neutral, general term to cover all such things.

I think that your micrographs reveal the presence of true interascal filaments. [The streaks in the hymenium of Verrrucariaceae are more tenuous and more disjointed.] The hyphae in the hymenium of your micrographs appear rather stout and they may be pseudoparaphyses at a relatively early stage before they have become more stretched and filament-like.

I am hitting a similar problem to you – doesn’t fit neatly into either Polycoccum marmoratum or P. opulentum. For the moment, I think the best you we can do is to give it a working name of ‘Polycoccum sp.’ put all the usual details on a spreadsheet, make sure you note the host, put the spore size and any other brief details in the ‘record notes’ column and specimen details including a number in the appropriate columns. In that way, the details will be in the ‘system’ and in theory anyone doing a project on, for example, Polycoccum and allied LFs on Verrucariaceae will at least have your specimen details. We may find that it belongs in another genus in due course but probably best to call it a ‘Polycoccum’ for the moment as a working hypothesis.

Hopefully there will be a relatively quick resolution but if not at least the details have been discussed and some information archived.

You could perhaps email Paul Diederich and link him to this post and see whether he gets anywhere with the information and images here.

[Mark Powell]

The spore size and shape is more reminiscent of Polycoccum. You perhaps had a difficult choice at couplet 20 in the draft lichenic. keys? This couplet separates LFs with interascal filaments (including Polycoccum) from those without. My advice would be, assuming you haven’t already done so, to make another concerted attempt to see whether or not any interascal filaments can be detected. Having mentioned the name Polycoccum, I don’t want to give the impression that I am at all sure that Polycoccum is the genus you are looking for. I don’t recognise your LF. If you look at couplet 39 in the LF pyreno. key, you will see two fungi which are reported on Verrucariaceae: Polycoccum marmoratum and Lichenothelia renobalsiana. I don’t know either of those myself but they might be worth investigating (if you find interascal filaments).

[Mark Powell]

I would agree with Neil. With the information we have currently (LGBI2) the combination of Nostoc photobiont and simple, mainly globose ascospores would lead us to call this Lempholemma polyanthes. In fact your material with the globose spores and slightly lobate thallus (“resembling moribund Collema auriforme“) is what LGBI2 calls “typical” L. polyanthes.

I have only recorded L. polyanthes once, in Somerset. In the East we get even trickier members of the ‘polyanthes group’ most of which we call ‘chalazanellum‘. Occasionally we come across similar ones with a better-formed thallus which we are tempted to call chalazanodes. However, I am not sure that we really understand these ones with ellipsoid spores and I wonder if they are ecological morphs. Unfortunately they aren’t common enough to get a real feel for them so we just have to make an attempt at interpreting LGBI2 and applying our best guess of a name.

Back to your lichen and I feel sure that you would be right to record it as L. polyanthes.

Mark

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