Hyperphyscia lucida

[John Skinner]

In July last year I visited the churchyard of the village of Charles in north Devon. An elder bush had been pruned and I brought back some twigs to list the lichens. On the twigs I noticed a strange Hyperphyscia which I thought might be H. lucida which I had read about in a paper by Arno van der Pluijm who had described the species in 2020. I sent him photos and he thought it might be H. lucida and he asked Henk-Jan van der Kolk to carry out DNA barcoding on the specimen. I have just heard that it is H. lucida and I mention it here to alert people of the possibility of this lichen being present. The Devon locality is 600km from the Netherlands site so perhaps it is also in other places in between.
H. lucida has wide overlapping shiny lobes but it is still a tiny foliose lichen like H. adglutinata. The soralia in H. lucida, like H. adglutinata are pustulate but often more aggregated and they tend to form a sorediate crust in the centre of the thallus and the soredia become isidioid. There is a thin varnish-like prothallus, very difficult to see on the Devon specimens.The description in Arno's paper is excellent.
I have also found it in Maxine's garden in West Down, on Philadelphus and Crataegus, in both cases on very thin twigs. It grows in very nutrient rich environments with H. adglutinata, Physcia tenella, Xanthoria parietina, Halecania viridescens and Lecania naegelii, also much green algae. There is a lot of muck spreading in the north Devon countryside and these nutrient loving lichens are increasing in abundance.
While witing for the barcoding result I have been searching for this lichen wherever I have travelled but no luck other than here in Devon. I have looked in Essex and London where H. adglutinata is abundant, also on the field meetings in north Hampshire and Nottingham. I feel sure it is waiting to be found. Please let me know if you find it.
Reference: https://doi.org/10.25227/linbg.01138

[Pluijm]

Hi John, I am not yet sure that the second specimen, from West Down is also H. lucida. On the particular photo from West Down you posted here, the thallus seems to have rather wide lobes, but it also shows discrete, crateriform soralia more characteristic for H. adglutinata.
Arno van der Pluijm

[Neil Sanderson]

John

Nice find, well spotted!

Neil

[maxieput901]

Hi Arno! Would you say the lobes turning up at the ends and the pale prothallus are the characteristic features to look out for?

[Pluijm]

Hi Arno! Would you say the lobes turning up at the ends and the pale prothallus are the characteristic features to look out for?

I always look for a combination of characters. In an ideal situation H. lucida has rather large dimensions, wide, very flat lobes with indeed sometimes upturned lobes, generally with a clear rim of transparent 'glue' surrounding the margins. The laminal soralia originate from pustules that are often situated on folds on the thallus. Hyperphyscia adglutinata can rarely (in shaded habitats?) also have somewhat upturned margins, but I have never seen this extensive borders of 'glue'. The neat rounded, isolated crateriform soralia are typical for H. adglutinata. Less well developed forms of H. lucida can be difficult to separate. Naming from photos can also be tricky.

[John Skinner]

I apologise for leading people astray,carried away by my enthusiasm. It is interesting however that much Hyperphyscia here in West Down, Devon, shows these very wide overlappiong lobes. Typical narrow-lobed H. adglutinata is also present. Whether that is significant or not, the fact remains that H. lucida has been recorded in Britain so it is worth continuing to look out for it.

[Mark Powell]

I am pleased that this topic has been discussed on the forum. I previously found specimens which I thought resembled H. lucida but remained uncertain about them. Yesterday I found a particularly convincing colony, on the trunk of a large sycamore tree in Bedford Cemetery and it was this recent discussion that perhaps prompted me to take particular interest in it. I will post some images here but I think I will continue to treat this occurrence as tentative until I have made a more thorough comparison with specimens which I consider are likely to be H. adglutinata.

The following features of my recent collection which lean me towards thinking it is H. lucida are: Pale grey thallus, with rather flat lobes, often becoming wider than 0.5 mm, in places upturned at the margins. Soralia arising from swollen pustules (where soralia formation can be discerned) and the soralia not remaining discrete and not crateriform but instead becoming confluent in mature parts. Narrow shiny prothalus present in places.

[Mark Powell]

After collecting some of what I consider fairly typical H. adglutinata, I now feel more confident that my specimen from Bedford Cemetery really is H. lucida. I will post a couple of side-by-side images, then one of presumed H. adglutinata, and then a section of what I claim is a poorly developed prothallus in H. adglutinata. The prothallus is perhaps a feature which is a little confusing and may lead to uncertainty and confusion if too much emphasis is placed on this character alone. While the shiny prothallus is considerably more conspicuous in my suspected H. lucida, traces of a similar but even thinner marginal shiny fringe can be seen in my specimen of H. adglutinata. When seen in section this is similar in structure to the prothallus of H. lucida, sparse hyphae extending into a gel matrix, but it is far less well developed. So, perhaps it is not a case of strict presence or absence of this type of prothallus but rather one of degree of development of it. It is perhaps like the distinction between Physcia aipolia and P. stellaris based on maculae, some accounts simplifying the situation to presence or absence of these, but in reality P. stellaris does possess maculae but they are very inconspicuous compared to those in P. aipolia.

[Neil Sanderson]

After trimming some Cotoneaster in my garden I also now have what looks to be Hyperphyscia lucida. This was handily growing right beside Hyperphyscia adglutinata (browner). Photos: