The names used on this web site are not necessary correct but are those that are in common use due to the lack of anything better.
When early mycologist first visited New Zealand and started naming our fungi they tended to give our fungi names of similar looking fungi found in the northern hemisphere. In not understanding that New Zealand been an island nation, isolated in the southern hemisphere and that our fungi had evolved along a different path.
This legacy of poorly named fungi has over the years caused considerable confusion compounded when you can now do an image search on the internet and see photos that look totally different in some case and the same in others. Add to this it's become common place now to do some form of DNA sequencing.
DNA sequencing is not only showing that fungi from the northern and southern hemisphere are in many case different but not always. Sequencing is also showing that existing NZ species have hiding under the same name other species.
A typical example it Cortinarius porphyroideus a common, colourfully and easily identified species. Resent sequencing show that there are three species hiding under this name which can not told apart without sequencing. So we should be technically be calling this Cortinarius sp. now. But how useful it that the Cortinarius genus is large with over 200 species many difficult to name or not named at all. So if some tells me they found a Cortinarius sp. how useful is that if they told me they found Cortinarius porphyroideus then I would know it like one of three purple Cortinarius species. a much useful name.