Observation 122677: Postia caesia (Schrad.) P. Karst.
When: 2012-12-15
No herbarium specimen

Notes: Isolated fruit body on wood, pores nearly round.

Proposed Names

-57% (1)
Recognized by sight
66% (3)
Eye3 Eyes3
Recognized by sight

Please login to propose your own names and vote on existing names.

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Very cool!
By: Martin Livezey (MLivezey)
2013-01-14 01:01:55 AST (+0300)

Thanks very much!

By: vjp
2013-01-13 23:03:45 AST (+0300)

“Molecular variation in the Postia caesia complex” – Yao, Pegler, Chase

If you can’t find it online i can send it to you.

DNA sequences of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA (nrDNA) and small-subunit of mitochondrial ribosomal DNA (mt-rDNA) were obtained from 12 different collections initially identified as either Postia caesia or P. subcaesia based on morphological criteria. Sequences of ITS from British collections separate into three clear groups, each with identical sequences, regardless of the lignicolous host and distribution. These British collections can be distinguished morphologically as two groups, (a) thick and larger basidiomata (1.5–5.0 · 2.0–6.0 · 3.0–15 cm) with a strigose to tomentose pileus and (b) thin and smaller basidiomata (0.5–2.0 · 1.0–2.5 · 1.5–4.0 cm) with a smooth pileus. The former were all collected from hardwoods and
the latter from both hardwoods and coniferous woods. Group (a) corresponds to one of the sequence groups, but group (b) displays two different sequences. Two collections from Norway, one from each of the morphological groups, exhibit further sequence variation within the ITS regions, although closer to those of British group (b). Representative sequences of mt-rDNA from each of the
three British ITS sequence groups remain distinct, but those from the two Norwegian collections, however, are identical to one of the British groups. Further comparison of basidiospore size revealed no clear distinction among these groups, although the ratio of spore length to spore width is generally greater in group (a). Although there is no clear separation of these collections into two species, there is a clear tendency of variation at both morphological and molecular levels, among them. Differences in morphology and DNA sequences do not warrant species recognition, but do demonstrate high variability within the species complex.

2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.”

It looks like you have group b, but, the paper doesn’t put a name to either group. The DNA and mating studies don’t help. I guess Postia caesia group fits best.

I agree
By: Martin Livezey (MLivezey)
2013-01-13 04:36:12 AST (+0300)

that the photo could be interpreted as Postia caesia. I have found it myself in the east.


But that observation as well as others on MO show a thick fruit body; I remember this to be as thin as T. versicolor. Maybe that is normal variation or maybe it is a different variety or species.

Created: 2013-01-13 02:59:16 AST (+0300)
Last modified: 2013-01-14 00:34:31 AST (+0300)
Viewed: 90 times, last viewed: 2017-06-15 14:27:05 AST (+0300)
Show Log