Auricularia pusio group

The fruit body has a rubbery texture and grows flat against the surface of wood, except that at the upper edge the fruitbody may grow out from the wood to create a short ledge. The upper surface of this ledge is densely hairy. Otherwise the fruitbody is brownish to grey and with numerous ridges or wrinkles. Neighbouring fruitbodies may fuse.

Spore print: white.

Look-alikes

The Auricularia pusio group is quite distinctive.

Why not identify these sightings simply as Auricularia pusio?

Auricularia pusio is a native species and the first published description appeared in 1881, based on material collected at Rockhampton in Queensland. It had long been synonymised with Auricularia mesenterica (a species first recorded in Europe) but the authors of the paper cited below thought that the fungi placed in mesenterica were a mix of species, with different mesenterica-like species in different parts of the world, and they re-instated pusio as a distinct species. This is the only mesenterica- like species they recorded for Australia.

On the Atlas of Living Australia (ALA) you find visual records of Auricularia mesenterica from various parts of Australia. That’s not surprising given that, for many years, Auricularia mesenterica was thought to be worldwide. It is also not surprising that in recent years people have taken to reporting sightings of Auricularia pusio and on ALA you find visual records of that species from the northern part of the Northern Territory, the east coast from north Queensland to Sydney and some spots a little west of the Great Dividing range.

The analysis by Wu et al used only two Australian collections identified as Auricularia pusio. The specimens were collected in the Kimberley region in 1988 and 1999 and the two collections are stored at the Kew herbarium in London. It is natural to wonder if, in a country as large and environmentally diverse as Australia, all mesenterica-like fungi are the one species. A search of Australian herbarium collections via the Australian Virtual Herbarium (AVH) database (on the 18^th of June 2024) showed 63 collections identified as Auricularia mesenterica. Apart from northern Australia (from the Kimberley east to north Queensland), there are collections from south-east Queensland and north-east NSW, including a couple inland of the Great Dividing Range (one from the Richard Underwood Nature Reserve in Queensland and the other from the Pilliga East State Forest in NSW). In the light of the Wu et al paper it would be very useful to re-examine those specimens (especially those outside the tropics) to see if they match Wu et al’s concept of Auricularia pusio. The only specimen of Auricularia pusio recorded on AVH is one from the 1800s, kept by the herbarium in  Melbourne, and which bears the same collection number as that quoted in the first published description of the species in 1881.

If one assumes that there is only one mesenterica-like species in Australia then Auricularia pusio is the name to use. If one wishes for evidence that  Auricularia pusio is widespread in Australia then ‘Auricularia pusio group’ is the name to use. I think it clear that the Wu et al paper is simply a good starting point for the study of mesenterica-like species in Australasia.

Incidentally, Wu et al reported one collection of Auricularia pusio from Zambia in Africa.

Reference

F.Wu, A.Tohtirjap, L.-F. Fan, L.-W. Zhou, R.L M. Alvarenga, T.B. Gibertoni & Y.-C.Dai, (2021), Global Diversity and Updated Phylogeny of Auricularia (Auriculariales, Basidiomycota), Journal of Fungi, 7, 933