Exidiopsis calcea query

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  • #30937

    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?

    #40940

    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

    #40941

    Andy Simpson wrote:


    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    The trouble with Peter’s 1993 key is that it’s a bit out of date.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

    #40942

    Just came across this – only six years late! The genus Exidiopsis awaits a DNA-based revision and is a bit of a mystery at the moment. I suspect we have many more species in the UK than there are names currently available. On the continent “Exidiopsis calcea” is the name given to a species that grows on dead attached branches of conifers (largely spruce) – as illustrated in Fungi of Switzerland. I have seen it in Germany and elsewhere where it is conspicuous and probably common. I have never seen this taxon in the UK, where our “Exidiopsis calcea” grows on dead attached branches and twigs of deciduous trees and shrubs – usually decorticated. It seems fond of garden shrubs like buddleia and flowering currant and is common, but not so conspicuous. Which of these two represents Persoon’s original species is moot. Our “Exidiopsis calcea” is packed with fine mineral matter and tends to turn patchily brownish wih age – but there may well be more than one species involved, since spore size is rather variable and some collections have quite prominent cystidia-like elements in the hymenium. File it away as Exidiopsis cf. calcea until we know better – or just pretend you never saw it!

    #40943

    PS I’m reading the wrong date. Less than three years late! Pretty good for me…

    #40944
    adampembs
    Keymaster

      Peter Roberts wrote:


      PS I’m reading the wrong date. Less than three years late! Pretty good for me…

      Welcome to our little group! :)

      #40945

      Thanks, Adam. Not sure I can be very useful, but maybe now and again something will jog a brain cell…

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