1cm wide Snow-white Polyporales

Can this small pore-bearing fungus (Polyporales ), approx 1 cm wide, be identified. The pores are very minute, barely visible with the naked eye. They were attached to a stick and I think they were facing down (hence not resupinate as the pic may indicate).

Thank you so much for these helpful notes. I was away from mycology for two days but today/tmrw I should do some investigations. The fruiting body has a hint of blue. The stick was found around and probably is of Pinus halepensis. I consult Bernnichia's book . I keep you posted. tnx.

Hello,

I have worked on this difficult polypore and consulted the last monograph by Berrnichia and maybe I have a conclusion between two species: This is the info I have

• Basidiome on a dead twig of Pinus halepensis in Malta (Xerophilic habitat)
• Basidiome with a slight bluish-grey tinge
• Basidiospores 4.5-6.0 um long x 1.5-2.2 um wide, allantoid (curved cylindrical with rounded ends) - but they are very hyaline, do not stain well, and are so difficult to have a focused outline - maybe they are 15% smaller due to measuring of an unfocused wall, yet I am sure the width is >1.5um wide.
• about 4 to 5 pores / mm (I counted the number of pores fitting in 1 mm as they are naturally present in the hymenium - not taking the mean pore width and dividing it by 1mm - I hope this is the way to measure this)
• The surface of the cap is smooth, felted but compact down to a smooth surface in a mature basidiome, somewhat pubescent at the stipe and margin.
• Hypha of the surface are smooth, sometimes becoming bluish-grey at the tip
• When added pieces of mycelium in congo red, the stain became momentarily dark reddish-black.
• Large clamp junctions.

With this data and using Polyporales keys (Berrnichia & Gorjon) I am in the P. caesia, P. simulans and P. mediterraneocaesia dilemma.

P. caesia is given as spores up to 5um while P. simulans up to 5-6 (now that's very borderline to base a distinction!) however these two are said to have pubescent pilear surface and P. simulans or borealic/northern species.

The surface of my specimen is pubescent at the stipe attachment then its pubescence is soften to a compact texture, which if assumed to be smooth, the identification will fall onto P. mediterraneocaesia.

The spores of the latter species(4.2-6.1 x 1.4-1.7) fits with those of my specimen, so does the smallish size, host, habitat and Mediterranean distribution but P. mediterraneocaesia is defined to have an encrusted/rough hyphae at the epicutis (assumable referring to the outer surface of the pileus) but my specimens have them smooth. I mounted them in KOH so I hope that would not provide some reaction on the crystals. Saying that I saw exceptional hyphae with a roughened surface (that was mounted in water).

P. simulans is a northern species so it could be ruled out for that reason.

Your comments are more then welcomed (P. caesia(/P.simulans) or P. mediterraneocaesia ?)

https://www.researchgate.net/publication/323855557_Postia_caesia_complex_Polyporales_Basidiomycota_in_temperate_Northern_Hemisphere

Thank you Frank x x x

I am happy to add another species to the Maltese Mycoflora

Merry Christmas to you and dear ones

best wishes

Steve