Observation 193070: Octaviania tasmanica (Kalchbr. ex Massee) Lloyd

Herbarium Specimen Available from H. Lepp Canberra Herbarium Australia.

Two small oval shaped fungi found beneath floor litter and existing with half of the body in the forest soil. The lower halves of both specimens when removed from their habitat showed a distinct yellow surface area. Micrographs were completed and are included in the summary. Also, a summary and comments by Heino Lepp,who has kindly assisted with the identification and additional notes. The find area is semi rainforest and a cleared area where forest inhabitants have been foraging for food. I have found this particular site to be productive on a number of occasions. Although we have been in drought there was light rainfall the previous night. The area is close to a fresh water stream which at present is not running. The overhead canopy is limited because of the drought. The ground is soft with a 4-6 inch topsoil. The closest trees are palms and some Eucalypts. Also some rain forest vines are scattered in the local area.
Notes By Heino, : Hello Ian

The two specimens you sent me are one of the native truffles, Octaviana tasmanica, parasitized by a species of Sepedonium, an anamorphic fungus. Both Octaviana sporocarps are well covered by the white-yellow mix of Sepedonium mycelium and asexual spores making it look very much as if it is in fact the truffle’s skin (or peridium, to be technical). If you carefully pull off some of that white-yellow layer, you find the truffle’s thin, dark brown peridium below. Sepedonium spores start off colourless but are golden yellow at maturity. Also, as your microscope photos showed, the Sepedonium spores have flatter as opposed to pointed apices, and they are about twice the diameter of the Octaviana spores (which are a paler yellowish in KOH and some show a slow but weak dextrinoid reaction in Melzers). You could say that it is appropriate for Sepedonium to parasitize Octaviana, since species of Sepedonium have been found on a variety of species of the boletales and Octaviana is placed in the boletales.

After finishing the examination of your collection, a literature search showed that species of Sepedonium have been recorded on several of the truffle-like members of the boletales, including species of Octaviana, with the earliest record seemingly dating to 1881 (but I haven’t seen that publication), reporting a European find.

The two specimens make a very worthwhile herbarium collection!

Proposed Names

29% (1)
Used references: Heino Lepp (Canberra Herbarium, Australia)
Based on microscopic features: Micrographs
86% (1)
Eye3 Eyes3
Used references: Heino Lepp Herbarium Canberra.
Based on microscopic features: Micrographs by kk
31% (2)
Used references: hyperparasite from notes

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so to which sp. does the blue belong?
By: Danny Newman (myxomop)
2015-09-30 14:16:06 CDT (-0400)

host or parasite?

Created: 2014-12-10 22:23:45 CST (-0500)
Last modified: 2016-04-23 20:19:33 CDT (-0400)
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