Taeniolella delicata LF on Lecanora hybocarpa?

Last month I took a necrotic Lecanora hybocarpa specimen from an unhealthy rowan (Sorbus acuparia) in Glandford, Norfolk (TG04/VC27). The thallus is infected with various lichenicolous fungi, including Unguiculariopsis thallophila and perhaps an as-yet undetermined mould-like hyphomycete.

There are also brown-black caespitose growths on the thallus, which appear to be an anamorphic dematiaceous hyphomycete — potentially Taeniolella delicata. I’ve included photographs and micrographs below, as well as a bit of explanation about this tentative identification.

However, if correct, this record would be the first not only for VC27 East Norfolk, but also for Norfolk as a whole. It would also be one of only a small handful of records for the UK — see https://britishlichensociety.org.uk/resources/species-accounts/taeniolella-delicata” class=”bbcode_url”>https://britishlichensociety.org.uk/resources/species-accounts/taeniolella-delicata. With that in mind, I’d be grateful for additional opinions.

In their monograph on Taeniolella (open access at http://dx.doi.org/10.3114/fuse.2018.02.06” class=”bbcode_url”>http://dx.doi.org/10.3114/fuse.2018.02.06), Heuchert et al say that T. delicata ‘is able to infect numerous lichen species of various unrelated genera and is one of the most common Taeniolella species’ (2018, p 113). There are records from many countries. The few UK records are fairly distantly scattered, suggesting that it’s widespread. It’s also been found on many Lecanora species, including in the UK, including species of the subfusca group, and including L. chlarotera s. lat. — according to Heuchert et al, the FGBI website, and the older Hawksworth LF keys (1983).

Considering also that a significant number of the UK records for T. delicata come from Suffolk, it would be no great surprise if my Norfolk specimen were indeed the same LF. The FGBI website calls T. delicata ‘almost certainly overlooked’ despite being listed as nationally rare.

Following the generic key in Heuchert et al, my specimen seems morphologically to be Taeniolella rather than another similar genus — brown colouration, mostly if not wholly immersed hyphae with superficial conidiophores (I think), not much branching, transverse septae only, and narrow conidiogenous loci (again, I think — it’s hard to tell the conidial cells from conidiogenous cells, which is apparently also characteristic of Taeniolella).

Following the tabular key to lichenicolous Taeniolella species in the same monograph, the three possibilities for Taeniolella on Lecanoraceae are T. delicata, T. lecanoricola, and T. pertusariicola. The latter two appear to be ruled out as follows:

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