I have found three species of Microthyriales on needles  of pinus sylvestris, and I can't  identified it.
Species nº1: Tiriotecios 80-100um. Entire margin. Asci tetrasporic. Spores with lateral cilia.
Species nº2: Tiriotecios 100-170um. Irregular margin, not fimbriate. Asci octosporics. Spores without cilia.
Species nº3: Tiriotecios 100-160um. Irregular margin. Asci octosporics. Spores with cilia on the side and at one end.

Looking at the book of Ellis & Ellis, he mentions three species on Pinus. Comparing with that, I think specie nº2 can be Stomiopeltis  pinastri. The nº 1, would be similar to Trichothyrina pinophylla, but with spores ciliated and asci tetrasporic. And Microthyrium pinophyllus similar to nº3 but with cilia also at one end.

What is your opinion?
Thanks, Greetings

SUSANA (Spain)

Ludovic Le Renard, 26-05-2020 21:44

Re : Microthyriales on Pinus sylvestris

Hello,

I recently completed my dissertation on thyriothecium-forming fungi, I would agree with your identification on overall. Ellis' taxonomy is slightly outdated, and the group still needs a lot of work before we can apply appropriate names.

I think those taxa can be classified based on the morphology of the scutellum (the covering plate) more than ascospores characters.

Species nº1: looks like it had an entire margin and a lower wall, making it a catathecium, typical of Lichenopeltella (formerly Trichothyrina). Your specimens is very similar to those I sequenced DNA from. The cilia are quite hard to see, even in Phase contrast illumination I had a hard time finding them (attached picture).

Species nº2: Stomiopeltis pinastri is the best possible guess, but the genus Stomiopeltis is polyphyletic. The hyphae of their scutellum tend to be untraceable back to the centre. This one may be an undescribed Microthyriales instead because it has radiate scuellum with anisotomous dichotomies and meandering doesn't involve much overlap so that we can trace it back. I attached one illustration from my dissertation that explains differences. The corresponding article is available here.

Species nº3: Most character of your specimen fit Microthyrium. In my view, it resembles more  thyriothecial taxa that grow below host cuticle (cf. Leptopeltis spp.) than Microthyrium (above cuticle) but there is no ilustration of habit. The files of cells in the scutellum do not branch very much distally, as I have seen in Leptopeltis, while they tend to branch throughout in scutella of Microthyrium spp. Additionally, good data on scutellum morphology is quite limited.

I hope that helps,

Cheers,

Ludo

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