Observation 1105: Postia caesia group

When: 2006-11-24

Collection location: Wilder Ridge, Humboldt Co., California, USA [Click for map]

Who: Nathan Wilson (nathan)

No specimen available

I did not take a spore print, but if you assume it has the correct spore color (blue or bluish-gray) then it keys out in Mushrooms Demystified as Tyromyces caesius. This name is synonymized with Postia caesius in the Index Fungorum. Oligoporus caesius is also listed as a synonym.

In the field it seemed a bit greener than it appears in these photos. When I saw it, it made me think of the blue-green polypore Debbie Viess recently mentioned on the BAMS website. Interestingly I saw the same little polypore the next day on the Sanctuary Forest foray. I made an herbarium collection of that specimen.

Overall it was very poor collecting in southern Humboldt county this year. I believe the reason was an early cold snap which shutdown most of the mycorhizal species.

Species Lists


Proposed Names

56% (1)
Recognized by sight: P caesia doesn’t occur in NA. There are 24 species in the complex of which 7 are documented from NA.
Used references: Miettinen et al. 2018

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= Observer’s choice
= Current consensus


Add Comment
Don’t know the story
By: Nathan Wilson (nathan)
2006-12-24 11:39:04 CST (-0600)

What I do know is that Index Fungorum lists Postia caesius as the correct name for this taxon and Postia caesius gets almost twice as many hits as Oligoporus caesius. Most of the Postia hits European. Also Swiss 2 only lists Postia and doesn’t even acknowledge Oligoporus as a synonym. I would guess that Gilbertson and Ryvarden (1986, 1987) list Oligoporus, but I don’t have a copy handy. I heard there was supposed to be a new edition out ‘real soon now’ about a year ago, but I haven’t heard anything further. If you’re interested in why it’s not Tyromyces check out Tom Volk’s page http://botit.botany.wisc.edu/toms_fungi/polypore.html.

By: Douglas Smith (douglas)
2006-12-24 11:10:00 CST (-0600)

Why Postia, instead of Oligaporus? (Or Tyromyces, or Polyporus…). I’m not sure I expect an answer here, but these polypore genera are starting to run wild… (Not to mention Jahnoporus…).