Observation 196646: Radiigera Zeller

Two small spherical shapes found at surface level in the area adjacent to a fresh water stream in a Semi-rainforest area. Both were easily lifted away from the surface, (which was covered by forest litter and debris). I photographed both together as they appeared to be matching. It was only when I bisected the spheres that a whole new scene prevailed. After some consideration I believe that both fungi are of the same genus and that one is immature and the other mature specimens. Both when cut were wet inside and slightly sticky.

Proposed Names

29% (1)
Recognized by sight
53% (3)
Eye3 Eyes3
Recognized by sight: The second, more mature specimen is definately a Radiigera, Ian. I have not seen this with basal rhizimes before. It is more typical that the entire sporocarp is buried. You might try looking for raised areas nearby. Important to note nearby trees and shrubs, Ian. This may well be a species novum.

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Eye3 = Observer’s choice
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Comment Courtesy Heino Lepp.


I reckon this is an immature Geastrum. Certainly the beak-like projection in the dissected immature specimen suggests an ostiole. Still, the photos and the specimens you sent made me read up about Radiigera – in particular a 1996 Mycologia paper by L.S. Dominguez de Toledo & M.A. Castellano (vol 88, pp 863-884) which revised the genus. They note that a significant difference is a well-developed endoperidium in Geastrum but a feature absent or poorly-developed in Radiigera. Of the two specimens you sent, one was still largely white inside and the other was dark brown. The attached photo shows a section through the peridium of the immature specimen (and a tiny bit of gleba came along as well). It looked to me like a well-differentiated endoperidium, about 60 mu thick. More impressive was a look at the cross-section of the peridium of the dissected mature specimen. While looking under the dissecting microscope I found a gap in the peridium, between what looked to be endoperidium and exoperidium. I could put a fine needle in there and, working gently, could run it along a bit and so easily separate endoperidium and exoperidium – just like a well-developed, but unopened Geastrum.



don’t be too sure about this name …
By: Debbie Viess (amanitarita)
2015-01-19 10:00:13 PST (-0800)

OZ is a hotbed of secotioid fungi, with estimates as high as 2,400 species! Here is a nice synopsis of their biology Down Under: http://www.anbg.gov.au/fungi/truffle-like.html

I would write to Jim Trappe and Todd Elliott, both of whom have done extensive work on secotioid fungi of OZ. They may be familiar with this species, or want to examine your material.

As always, great work, Ian! I can see that Jan./Feb is a better time to visit OZ than in April!

Created: 2015-01-18 22:58:53 PST (-0800)
Last modified: 2015-06-24 02:21:53 PDT (-0700)
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