Claussenomyces ‘atrovirens group’

The fruit body is disc-like, saucer-like or somewhat cup-like in shape and in technical terminology it is known as an apothecium. The apothecia are stemless, pale to dark olive green, rubbery or somewhat gelatinous and about half a millimetre in diameter.

The apothecia appear on dead wood and very many may appear within a few square centimetres.

The spores are colourless and ellipsoid (but one end may be well extended so as to give a spore a club-like appearance).They are multicelled with a number of cross-walls across the shorter dimension but they may also have some cross-walls aligned along the long axis of the spore.

The species Claussenomyces atrovirens is known from various countries but I cannot say whether, in Canberra, we have atrovirens proper or something  akin to atrovirens, hence the use of ‘atrovirens group’.

Look-alikes

I think that if you see something of this colour, size and texture you should be safe in assuming Claussenomyces ‘atrovirens group’. Of course, size and colour also make it easy to overlook the ‘atrovirens group’.

If you search for information about Claussenomyces in Australia you will find many references to Claussenomyces australis, a species described in 1978, based on specimens collected in Victoria. Fresh apothecia of this species may be up to 25 millimetres in diameter and are dark green to black and gelatinous. It has been argued that this species does not belong in Claussenomyces because (1) the apothecium exudes a purplish pigment in a weak aqueous potassium hydroxide solution (something known as an ionomidotic reaction) and (2) the spores are single-celled. Those features make it an anomalous member of the genus and so you may also see this fungus referred to as Ionomidotis australis.