Observation 16299: Exidia plana Donk (Site ID) (Exidia nigricans)

When: 2009-01-14

Collection location: Bovec basin, East Julian Alps, Posočje, Slovenia [Click for map]

Who: amadej trnkoczy (amadej)

No specimen available

Exidia plana var plana
Black Witch’s Butter

Date: March 17. 2008
Lat.: 46.34708 Long.: 13.56282
Code: Bot_248/2008-5969

Habitat: Light mixed wood, 30 cm (one foot) above ground, S faced slope, S oriented, partly shady, exposed to rain, precipitations ~ 3.000 mm/year, average temperature 8-10 deg C, altitude 580 m (1.900 feet), alpine phytogeographical region.
Substratum: rotten debarked deciduous tree stump

Place: between Zavrzelno settlement and Ravni laz, north of Bovec, East Julian Alps, Posocje, Slovenia EC

Nikon D70 / Nikorr Micro 105mm/f2.8


Proposed Names

76% (2)
Recognized by sight
Used references: personal coomunication Mr. Gregor Podgornik, NAC, Tolmin, Slovenia EC
65% (2)
Used references: Exidia glandulosa (Bull.) Fr. (sensu Bresadola, Jahn, Neuhoff, Ricken) is still the currently used name for this species. Exidia plana Donk is a synonym, and now also Exidia nigricans (With.) P. Roberts. Time will tell if the case is strong enough for the last proposal..

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

= Observer’s choice
= Current consensus


Add Comment
By: Paul Derbyshire (Twizzler)
2010-04-10 03:53:13 PDT (-0700)

“Micro features are almost impossible to use in this genus. The shape and size of spores and basidia are extremely variable within the species, and will not serve as diagnostic. You will have to rely on macro features.”

That certainly makes for a refreshing change. :)

Micro features
By: Irene Andersson (irenea)
2010-04-10 03:22:17 PDT (-0700)

are almost impossible to use in this genus. The shape and size of spores and basidia are extremely variable within the species, and will not serve as diagnostic. You will have to rely on macro features.

I think the best way to learn the difference is to Google for pictures of “Exidia truncata” resp. “Exidia plana” (to avoid confusion with different interpretations of the name glandulosa). That’s how Marek Snowarski solved the problem at his site, and perhaps that’s the way it should be done too:

(the only result for “Exidia nigricans” is your own obs here at MO :-)

Thank you Irene for your in depth explanation.
By: amadej trnkoczy (amadej)
2010-04-10 00:52:44 PDT (-0700)

May be you know a place on net where I can find features distinguishing these two species?

My opinion
By: Irene Andersson (irenea)
2010-04-08 12:15:01 PDT (-0700)

I’m not sure if the pictures in CalPhotos that are named glandulosa, are glandulosa or very densely growing truncata..

The name glandulosa has been confusing for a long time, and it didn’t help much that Donk decided to pick up the old name plana for one of the two black species with warts that had been called glandulosa, and interpreted the name glandulosa as the other one that we have been calling truncata.

The last decades there has been two major opinions on the use of the names. One is represented by IndexFungorum, british mycologists and others too, here and there, and they follow the interpretations that were made by Donk 1966. Even the danish Mycokey follows the same nomenclature, but the danish checklist doesn’t..

I prefer (of course) the scandinavian checklists that represent the other opinion – the former interpretation of the names (the reason is that Fries actually described glandulosa and truncata differently and rather well), the use of the name glandulosa for what Donk called plana and Roberts’ nigricans; and truncata for what some others call glandulosa. No national checklists anywhere recognize all these names as different species, only two of them (with different ideas of synonyms). You may have noticed that the british checklist considers truncata a synonym of glandulosa. So far, I haven’t seen any keys or books naming or describing more than two black species either.

I don’t know if I can manage to make this issue less confusing. An example maybe..
Here’s one of Exidia truncata (syn: Exidia glandulosa sensu Donk):

I’m also pleased to see both species with the right :-) names in Yves Deneyer’s photo gallery

Since this name game definitely isn’t settled, maybe it would be a good idea to add in who’s sense we use the name glandulosa (Donk for one of them, and Neuhoff for the other..?).

I am confused now
By: amadej trnkoczy (amadej)
2010-04-07 13:17:29 PDT (-0700)

Sorry Irene, but I am confused now. Index Fungorum has Exidia plana Donc Persoonia 4(2): 228 (1966) as a ‘current’ name


and Exidia glandulosa sensu auct. p.p.; fide Checklist of Basidiomycota of Great Britain and Ireland (2005) as its synonym. This observation was checked by Mr.Gregor Podgornik, NAC (Natural History Center), Tolmin, Slovenia and recognized as E. plana.

I was taught by Mr Podgornik that there are two black Exidia species in my region E. glandulosa and E. plana, the latter having distinct ‘warts’ and more ‘planar’ habitus.

What I think is E. glandulosa is shown here (more ‘brain’ like and smoother surface)


Should I consider this observation and that published at CalPhotos the same species (for the time being)?

Thanks for your explanation in advance.