Lecanora hybocarpa auct. br. in France in 1956, and some thoughts

In my previous post above, I suggested that William Nylander had changed his mind at least once about the diagnostic characters of Lecanora chlarotera, a species he described somewhat differently three times (1872a, 1872b, 1891). I pointed to Nylander’s differing descriptions as an example of what Lucie Kohler, following August-Marie Hue, called the ‘greatest confusion’ of the ‘old lichenologists’ about the Lecanora subfusca-group, to which L. chlarotera belongs (Hue, 1903; Kohler 1956, p 167). However, after further research, I’ve revised my opinion: it was Hue who was confused about Nylander’s descriptions.

In this post, I’ll argue not only that Hue was confused about Nylander, but also that Nylander might have anticipated one important element of the subfusca-group classification scheme in use today: the placement of epithecial granules either in a defined layer above the tips of the paraphyses, or also descending between them. Adolf Hugo Magnusson (1932) was the first to develop the modern scheme, which was extended and elaborated by Josef Poelt (1952) and Irwin Brodo (1984). And though Kohler was wrong to follow Hue in ascribing utter confusion to ‘old lichenologists’ such as Nylander, she was right to criticise Hue for rejecting the diagnostic value of epithecial granules in the subfusca-group.

I also intend for this post to serve as background for future posts investigating in detail how the British concept of L. chlarotera came to be, and how it obscured the existence of another subfusca-group lichen, which was there all along: L. hybocarpa auct. br. But that’s for later.

For now, let’s turn back to Hue’s confusion about Nylander and epithecial granules. Hue certainly knew that epithecial granules could be seen in some subfusca-group species:

Often, it [the epithecium] is bare. Sometimes it is full of small granules of a dark yellow, and then the epithecium is called ‘granular’ — epithecium granulosum. This is an inaccurate expression, since the granules are not attached to the paraphyses, and they are easily dissolved in potassium hydroxide. Rarely, the granules cover the paraphyses along their whole length. (Hue, 1903, pp 32-33, my translation).

Yet as we’ve said, and as Kolher noted, Hue thought that the epithecial granules were not reliable characters for species identification. What’s more, he specifically criticised Nylander for relying upon them to separate some subfusca-group lichens:

In 1867, in Triana and Planchon, Prodr. Flor. Nov. Granat. Lich. Supplem., p 543, Mr Nylander attributed to this chlarona-variety [of L. subfusca Ach.] — which he later made a species in its own right — the following diagnostic characters: a whitish, thin, almost smooth or slightly rough thallus; a finely crenulated margin to the apothecia; a granular epithecium and a hymenial gel turning blue in iodine, with the asci taking a violet or reddish-violet tint. Then, in 1872, in his Observ. lichenol. Pyren.-Orient. in Flora p. 550 — published in a volume the following year — he [Nylander] separated L. chlarotera Nyl. from [L. subfusca var.] chlarona as a new species, distinguishing it from the latter by the more crenulated margin of the apothecia, the non-granular epithecium, the hymenial gel coloured intensely blue by iodine, and the longer spermatia. At first glance, none of these characters could suffice for describing a new species. A few crenulations more or less indicates nothing; the colour of the hymenial gel, i.e. the paraphyses, is the same in both; and lastly, it is not specified how much longer the spermatia are. The only distinctive character that remains, then, is the epithecium, granular or not. But we will see that there are very regularly furrowed apothecia with a granular epithecium, and very little furrowed apothecia with a non-granular epithecium. … What’s more, apothecia with a granular and a non-granular epithecium can be found in the same individual. Consequently, this character, which Mr Nylander regarded as primary, is inconstant, and only one and the same variety exists [viz. L. subfusca var. chlarona]. (Hue, 1903, p 74, my translation).

But Hue was in error. Nylander did not in fact distinguish between a granular epithecium for L. subfusca var. chlarona and a non-granular epithecium for L. chlarotera. Nylander distinguished between them in a rather more subtle way: by the placement of granules between the tips of the paraphyses, or only atop them. Hue, who did not think epithecial granules important, failed to grasp Nylander’s meaning.

Remarkably, in according such importance to both the presence and the placement of epithecial granules, Nylander was anticipating today’s Magnusson/Poelt/Brodo scheme. For this reason alone, it’s worth examining in detail what Nylander actually wrote, beginning with the description of L. subfusca var. chlarona that Hue cites:

Var. chlarona (Ach., Lich. U., p 397; Nyl., l. c. [Lich. Scandinav.], p. 160).—Thallus white, thin, sublaevigate or subrugose, determinate; apothecia pale flesh colour or pale dull red (0.5-0.9 mm diam.), with a crenulated thalline margin, constricted; spores 9-15 µm long, 5-8 µm wide; paraphyses slender, inspersed at the tips (at the epithecium) with yellowish granules. (Nylander, 1867, p 543, my translation).

Note that Nylander carefully distinguishes between the paraphyses and the epithecium: he uses the latter term to refer only to the surface of the apothecium, i.e. the surface formed by the tips of the paraphyses. Moreover, Nylander says that it’s the paraphyses themselves that are inspersed with granules, albiet at their tips: ‘paraphyses graciles apice (epithecio) granulis lutescentibus inspersae’. In fact, this translation of the Latin is conservative: another valid translation is ‘paraphyses slender at the tips (at the epithecium), inspersed with yellowish granules’. But Hue failed either to notice this distinction, or to consider it significant, saying only that Nylander described the chlarona-variety as having a ‘granular epithecium [épithécium granulé]’.

Further evidence that Nylander intended a more subtle distinction between granular epithecium and granular paraphyses comes from his descriptions of L. chlarotera, which as Hue noted he distinguished from the chlarona-variety. According to Hue, Nylander wrote that the epithecium of L. chlarotera was non-granular, citing his December 1872 description in the journal Flora. But Hue was incorrect here, and perhaps he was even being a bit disingenuous. He knew that Nylander had described L. chlarotera three times, having cited all three descriptions in his 1903 paper, and what’s more he knew that:

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The only way to make consistent sense of these three descriptions is to understand Nylander to mean that the two lichens differ not in having epithecial granules — since they both do — but in the placement of the granules. Unlike in the chlarona-variety, the paraphyses of L. chlarotera are not inspersed with granules (‘paraphyses non inspersae’), yet its epithecium is still formed of a layer of granules atop the paraphyses (‘epithecium inspersum’).

But doesn’t this conclusion amount to absolving Nylander of an error while simultaneously attributing one to Hue? Even so, they cannot both be correct, especially considering that Hue claimed to have examined two specimens that Nylander determined as L. chlarotera — including one from the Canary Islands to which Nylander explicitly referred in his 1891 description of L. chlarotera with epithecium inspersum — and found them both to lack any granules (Hue, 1903, p 77-78)!

Ultimately, the balance of evidence appears to me to favour Nylander over Hue — not only the evidence above, but also the following evidence:

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I’d like to add yet a further piece of evidence, which would conclusively decide the case: an examination of the Canary Islands L. chlarotera specimen, which Nylander described as having an epithecium inspersum, and Hue described as having an épithécium non granulé. The specimen was collected in 1845 or 1846 by Eugène Bourgeaux on behalf of Philip Barker Webb (Nylander, 1891; Raymond, 1972). I believe it can be found today in the Webb collection in the Herbarium Centrale Italicum in Florence, but I don’t have any access to it.

Be that as it may, Hue’s own subfusca-group classification scheme, which prioritised external morphological characters such as the shape of the thalline margin, was superseded by the Magnusson/Poelt/Brodo scheme that I argue Nylander anticipated in a small way. For more, see my previous post above.

And as I discussed in that post, Neil Sanderson’s 2019 discovery of L. hybocarpa auct. br. suggests that the Magnusson/Poelt/Brodo scheme might require further revision, at least for the British Isles.

In future posts, I’ll turn back to that point, trying to shed some light on it by investigating how the British concept of L. chlarotera came to be.

REFERENCES

Brodo IM (1984). The North American species of the Lecanora subfusca group. Beihefte zur Nova Hedwigia 79: 63–185.

Brodo IM & Vitikainen O (1984). The typification of Lecanora subfusca (L.) Ach., its varieties and some of its related taxa published before 1850. Mycotaxon 21: 281-298. https://www.researchgate.net/publication/285029816_The_typification_of_Lecanora_subfusca_L_Ach_its_varieties_and_some_of_its_related_taxa_published_before_1850.” class=”bbcode_url”>https://www.researchgate.net/publication/285029816_The_typification_of_Lecanora_subfusca_L_Ach_its_varieties_and_some_of_its_related_taxa_published_before_1850.

Hue A-M (1903). Causerie sur le Lecanora subfusca Ach. Bulletin de la Société Botanique de France 50: 22-86. https://www.biodiversitylibrary.org/item/272970” class=”bbcode_url”>https://www.biodiversitylibrary.org/item/272970.

Kohler L (1956). Remarques sur les Lecanora corticoles du group subfusca: Leur répartition dans les Alpes du Dauphiné. Revue bryologique et lichenologique 25: 167-182. https://www.biodiversitylibrary.org/bibliography/169357” class=”bbcode_url”>https://www.biodiversitylibrary.org/bibliography/169357.

Magnusson AH (1932). Beiträge zur Systematik der Flechtengruppe Lecanora subfusca. Meddelanden Från Göteborgs Botaniska Trädgård 7: 65–87.

Nylander W (1867). Lichenes. In J Triana & JE Planchon, Prodromus Florae Novo-Granatensis: Cryptogamie. https://bibdigital.rjb.csic.es/records/item/9742-prodromus-florae-novo-granatensis-cryptogamie” class=”bbcode_url”>https://bibdigital.rjb.csic.es/records/item/9742-prodromus-florae-novo-granatensis-cryptogamie.

Nylander W (1872a). Observata lichenologica in Pyrenæis Orientalibus. Bulletin de Société Linnéene de Normandie 2(6): 256-328 https://www.biodiversitylibrary.org/item/37520” class=”bbcode_url”>https://www.biodiversitylibrary.org/item/37520.

Nylander W (1872b). Observata lichenologica in Pyrenæis Orientalibus. Flora 55: 424-431 & 546-554. https://www.biodiversitylibrary.org/item/971” class=”bbcode_url”>https://www.biodiversitylibrary.org/item/971.

Nylander W (1891). Lichenes Pyrenæorum Orientalium: Observatis Novis. https://catalog.hathitrust.org/Record/100653227” class=”bbcode_url”>https://catalog.hathitrust.org/Record/100653227.

Poelt J (1952). Die Lecanora subfusca-gruppe in Süddeutschland. Berichte der Bayerischen Botanischen Gesellschaft 29: 58–69. https://www.bbgev.de/_files/ugd/f05de5_d67aa0972cb04a418c12edec88586a2f.pdf” class=”bbcode_url”>https://www.bbgev.de/_files/ugd/f05de5_d67aa0972cb04a418c12edec88586a2f.pdf.

Raymond M (1972). Bourgeaux, Eugène. In Dictionary of Canadian Biography, vol 10. http://www.biographi.ca/en/bio/bourgeaux_eugene_10E.html” class=”bbcode_url”>http://www.biographi.ca/en/bio/bourgeaux_eugene_10E.html.

[attachment=1]H-NYL 27347 Lecanora chlarotera lectotype 1.png[/attachment]

[attachment=0]H-NYL 27347 Lecanora chlarotera lectotype 2.png[/attachment]

Many thanks for your reply, Alain. Yes — despite Brodo’s (1984) work, some question does indeed seem to remain as to whether the size and placement of the epithecial granules are completely reliable for separating species.

That said, not even for Brodo is the placement of epithecial granules definitive — i.e. whether only on the epithecial surface, or descending into the hymenium. Granule placement is just one diagnostic character among others, though it’s the main one separating Lecanora chlarotera and L. hybocarpa auct. br., at least on current British conceptions.

Your findings about the calcium oxalate crystals of L. chlarotera are fascinating. Presumably you mean the large crystals in the amphithecium? It certainly seems reasonable that the lichen would deposit more calcium oxalate as it ages, in the same way that our kidney stones — also calcium oxalate — grow larger as we ourselves age.

But the small granules ‘inspersing’ the epithecium of Lecanora chlarotera aren’t composed of calcium oxalate. They dissolve in K, whereas calcium oxalate doesn’t. The compound is ‘chlarotera-unknown’, I believe, and the granules seem to serve an anti-herbivory function (on this point see Malíček, 2014, cited above).

My posts above refer to the size and placement of these small crystalline granules in the epithecium, not the large calcium oxalate crystals in the amphithecium. Lucie Kohler (1956) concluded that size of epithecial granules, not placement, was diagnostic. But Magnusson (1932), Poelt (1952) and Brodo (1984) concluded otherwise.

Many thanks for your reply, Neil. I hope you don’t mind my inadvertent elevation of your work from ‘elucidation’ to ‘discovery’! But considering that Lecanora hybocarpa auct. br. seems unlikely to be the same taxon as the North American L. hybocarpa, perhaps your work does indeed sit somewhere in between the two levels.

Grateful for the pointer to the entry in LGBI2 for L. hybocarpa. I feel fairly keenly the lack of this volume on my shelf. Three times now I’ve thought I had a used copy in my grasp, but it’s eluded me. If you know of anyone looking to sell their copy, I’d be a willing buyer.

It’s amazing to learn that our current concept of L. chlarotera s. str. may still be obscuring other cryptic taxa. Looking forward to hearing more about your investigations as they develop. LGBI3 suggests that, in addition to the potential relationship to L. sinuosa, the same may be true of L. hybocarpa auct. br. Are you able to shed any further light on that?

Thanks again for your interest in my posts above. I hope to add soon those promised further posts about the development of what you call the ‘expansive field concept’ of L. chlarotera in use here in Britain before 2019.

Many thanks, Alain. I’d be very interested to hear what you discover from this study.