Fungus Unknown to Science — RRfu2
Field names are used by some for referring to identifiable species for which a scientific name is not known. As part of numerous fungi forays with the Field Naturalists Club of Victoria we have been doing so for many years. One such species occasionally found by the group was recorded as Mycena 'tiny blue lights'. We found it on the dead rachises of soft tree-ferns and having a reusable name for it allowed us to know what we're talking about and be able to reference previous sightings. Turns out that this tiny mushroom is more widespread than we knew and in 2016 it was described as Mycena lazulina from Japan!
The point is some unnamed fungi are readily recognizable — such is the case with this species. Although it may not have a name it is a yellow disc fungus (to 5mm diameter) fringed with wavy serrations and with a short, dark stipe. It is usually gregarious (sometimes solitary) and so far has only been found growing on dead branches and twigs of Nothofagus cunninghamii.
In the last couple of years I have been tagging unknown but identifiable fungi with RR (my initials), fu (for fungi — not what you were thinking) and a number. RRfu1 turned out to be Cudoniella clavus, previously unknown for Australia. I found pictures of these online while trying to identify another fungus and, once they were confirmed, was able to update my old records.
I recorded these yellow discs for the first time in 2014 and have since tagged them with "RRfu2". They appear to belong to the Helotiales order of fungi, possibly in the Helotiaceae family. As I appear to be the only one to find and photograph them they don't have a field name but 'yellow beech discs' springs to mind. They are uncommon but certainly not rare (I'm surprised nobody else has recorded them before) — I tend to find them at least a couple of times each year (actually 6 times so far this year).
Links
RRfu2 tagged records on iNaturalist
my Unknown But Identifiable Fungi