Being cream to light brown in colour, this fungus can be somewhat inconspicuous, but it features some interesting characteristics, most notably the fertile under-surface. The white to cream pores are 'coffin'-shaped, increasing in size from the rim to the centre. Pore shape, along with other features, makes Polyporus arcularius reasonably easy to identify. Sore print is white.
Scaley, but smooth cap surface with central depression
Caps with a diameter more than 100mm have been reported, but the specimens I have found have not exceeded 60mm, and have more commonly been between 30mm and 50mm. The light brown cap is scaley but smooth to touch, with a central depression. This depression can range from a dimple to a shallow 'funnel'.
The cap margin is lined with fine white 'hairs', which is another identifying feature of Polyporus arcularius. Flesh is tough, white and very thin.
Notice the way in which the pores meet the stem. This attachment is described as sinuate or decurrent.
The stem is central, light to dark brown, smooth, but often with darker brown scales or blotches. Polyporus arcularius fruiting bodies are found on dead wood (native and exotic) in a variety of habitats from rainforest and woodland, to paddocks and urban areas. I am unsure as to its distribution in Australia.
Smooth concentric (in rings) scales, and 'hairy' margin
My sightings of Polyporus arcularius
[This with be updated with further sightings]
Hunter Valley, NSW - Unimproved grazing paddock on fallen timber - Nov.
Hunter Valley, NSW - Woodland on fallen timber - Nov.
Hunter Region Botanic Gardens - Heatherbrae - Woodland and grassed areas on fallen timber - Nov.
Barrington Tops National Park, NSW - Rainforest floor on fallen timber - Mar, Apr, Nov.
Hanging Rock, NSW - Pine plantation on fallen timber - Apr.
Pilliga Forests, NW NSW - mixed native forests - Oct 2010, Nov 2010
Baradine, NSW - residential area, stump Jun 2010, on lawn (buried timber) Oct 2012.
Freeman's Waterhole, NSW - mixed forest May 2011
Notice the inrolled edge of the juvenile fruiting body in the background.