It looks like Entoloma tjallingiorum. See:

https://www.google.ca/search?hl=en&site=imghp&tbm=isch&source=hp&biw=980&bih=1183&q=entoloma+tjallingiorum&oq=entoloma+tjallingiorum&gs_l=img.3...3561.3561.0.4796.1.1.0.0.0.0.157.157.0j1.1.0....0...1.2.64.img..1.0.0.Cbk6s3jhJKE

Dear Attila,

I send you an informational  recource "Entolomatoid Mushrooms":

http://www.mushroomexpert.com/entoloma.html

Is Entoloma according these information a new variety???

My best regards

Vladimir

A very puzzling little Entoloma, Attila!  I've never heard of a carbonicolous species in this genus, and it does indeed look like it's a burn site species (the resemblance with other carbophilic agarics is also amazing). I suggest that you contact Dr. Olga Morozova at the Komarov Botanical Institue, she's an Entoloma expert and she's helped me with my unidentifiable little Leptonias many times.

All the best,

Tatiana

Dear Tatiana, Vladimir and Santiago!

Thank You all for the help!

Dear Attila!

I know one species which could grow on fireplace. The holotype collection of Entoloma graphitipes E. Ludw. (sect. Undati) was found on a fireplace in Germany. Your picture and description fits rather well with this species.

Bálint

Dear Bálint!

Many thanks your useful help!

Attila

Dear Attila,

According to your picture and the data it is a really interesting species. But some characters which could confirm the identity of the species are missing. Entoloma is a really large genus and I am not sure whether your species is the same as Entoloma graphitipes and for sure It is not E. tjallingiorum.

E. tjallingiorum should have blue stipe and violaceous tinges on cap as well cheilocystidia, while your collection does not possess cystidia.

Entoloma graphitipes is recently described species which type collection occurred only partially on burnt ground and few other collections from Spain are not found on burnt ground. So it seems that occurrence on burnt ground is not decisive for identification of E. graphitipes. Other character which is problematic is pileus cuticle. Fruitbodies in your collection have small squamules on pileus and it is not translucently striate. Fruitbodies of E. graphitipes have mostly smooth pileus which is translucently striate up to the center. Also you did not specify whether your collection has clamps at the base of basidia, the type of pileipellis and pigment which are important characters for this group.

According to the spores your species belong to the group around Entoloma rusticoides which contain around 10 morphologically pretty close species. I am sending you the article which treat this group in Europe with the identification key. Your species could be a new one for science or E. flocculosum which has squamules on pileus. But as I said some additional characters could help. Maybe DNA could help in the identification.

If you have any additional questions just ask.

Best wishes,

Armin

Dear Attila,

nice photographs ! The squamulose pileus and the growth on burnt ground (see Noordelos, Fungi Europaei 5, pag. 627) are quite typical for E. flocculosum (Bres) Pacioni whose holotypus was picked up in northern Italy (not far from Hungary) by Giacomo Bresadola.

Other characters fit quite well (isodiametrical spores, lack of cheilocystidia, odourless basidiomes and so on)

Please let me know what you think about it.because I could be wrong, of course.

I am always at your disposal.

All the best.

Eliseo

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Dear Armin and Eliseo!

Thank you both the very useful help! I am confused, because in Vila's contribution about the E. rusticoides group (attached by Armin) I did not find a 100% match with any of the species. Still, I think it is E. flocculosum. In my fungarium, I can't find the exsiccatum, I have only the spore print. If I find the sporocarps, it will be necessary the molecular study.

In autumn, I have a lot of field trips, and many sporocarps, so several findings sometimes lost... usually the most important ones...

I wish You the best!

Attila

Dear Attila,

Do not worry too much! This group (around E. rusticoides) is difficult one, and needs further research. Material from different parts of Europe (and worldwide) should be included to clarify taxonomic positions of species in this complex.

Best wishes,

Armin

Dear Attila,

in my opinion morphologically your collection matches Noordeloos' description of E. flocculosum quite well, however I agree with Armin  on the fact that this complex of taxa needs further studies, especially more molecular investigations.

All the best.

Eliseo