Exidiopsis calcea query

[MykoGolfer]

Found on the underside of a fallen branch, hard, brittle and yellowish, this was treated as a corticioid. It softens in damp conditions becoming whiter. The spores are allantoid, 15-16 x 5um, a few to 20um, some irregularly shaped, with oily contents. Also some round structures that could be cystidia. Mycokey suggests Exidiopsis. There is no suggestion of pink which excludes E. effua. The only other option I can find is E. calcea.
I came across a post on this forum from Steve dated 23rd April 2016. The pictures of his specimen are very similar.
I ask the same question, could this be Exidiopsis calcea?

[Andy Simpson]

Hi Mal,
From description and images this does look like Exidiopsis calcea. I have two collections of E. calcea, both with spores to 18-20 long, width 5-7.5. Oil drops also noted in both collections. In several seperate collections of E.effusa, spores never reaching these dimensions. Cystidiols can be present, 23-75 X 2-10, subcylindrical, subclavate or fusiform(from Resupinate of Hampshire). There is a key to British species by Peter Roberts in Mycological Research 97 (4).
Andy

[Chris Yeates]

Hi Mal,
From description and images this does look like Exidiopsis calcea. I have two collections of E. calcea, both with spores to 18-20 long, width 5-7.5. Oil drops also noted in both collections. In several seperate collections of E.effusa, spores never reaching these dimensions. Cystidiols can be present, 23-75 X 2-10, subcylindrical, subclavate or fusiform(from Resupinate of Hampshire). There is a key to British species by Peter Roberts in Mycological Research 97 (4).
Andy

Hi

The trouble with Peter's 1993 key is that it's a bit out of date. In it he states: "At present only four Exidiopsis species have been reported from Britain, three of which have been found in Devon and are described here. The fourth species, Exidiopsis calcea (Pers.) Wells, has been frequently confused with E. effusa and its occurrence in Britain requires confirmation."

Now six species are accepted on the GB Basidio list (including E. calcea).

Chris