Observation 224867: Acarospora A. Massal.

When: 2015-12-07

Collection location: Monterey Co., California, USA [Click for map]

Who: J-Dar

Specimen available

On igneus rock, a mixture of serpentinite and other stuff. Full sun exposure in semi-arid grassland habitat.

Thallus chocolate to dark brown, areolate to squamulose, plane to rounded convex, shiny, K-, C-. Squamules elevated above substrate on a broad attachment, not sure if it counts as a stipe or not. Apothecia immersed, deep red-brown to blackish, concave, I think without a parathecial crown (see photo). Medulla white, C- (observed at 400x). Algal layer seems even, without interrupting hyphal bundles. Asci with many spores, spores simple, hyaline, ellipsoid. Two spores measured 3.75/4.5 × 1.9/2.8µm. Diameter of paraphyses base not measured, but in relation to nearby spores they appear to be less than 2.3µm wide (see photo).

The lichenicolous fungi Endococcus parasitising this specimen is represented in a separate observation.


Ascus at 400x in water
Immersed apothecia in center squamule. Small black dots are a parasitic lichenicolous fungi in the genus Endococcus.
Upper cortex cross-section, in water @ 400x with KOH.
Top of apothecia is to the left. Spores shown with measurements. Asci and paraphyses apparent but not clear.

Proposed Names

57% (1)
Recognized by sight
-28% (1)
Used references: Nash Sonoran Flora
28% (1)
Recognized by sight

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= Observer’s choice
= Current consensus


Add Comment
Spores might not be important for Acarospora
By: Jason Hollinger (jason)
2015-12-30 23:10:17 CST (-0500)

I mean, outside of the fact that there are a bazillion of the little things in each ascus. More important is whether it is C+ or K+, and anatomy of the areoles — are they broadly attached, somewhat constricted but still broadly attached (“gomphate”), attached by a relatively narrow column (“stipitate”), that sort of thing. Also, check whether the cortex hyphae form little bundles which plunge down into tha algal layer resulting in a jagged or interrupted algal layer. C test is best done on a section of an areole or apothecium at 100×. So easy to miss under the dissecting scope.

As if Acarospora wasn’t difficult enough
By: J-Dar
2015-12-30 22:36:00 CST (-0500)

But dang nabit I think you are on to something. I just don’t see that there were paraphyses discernable at maturity of the asci. If you take the spore end as attenuated, and believe that it is just barely such, then I can see it in some spores. Endococcus stigma might be the best name we can give this lichenicolous fungi at this time (the only species of the genus in the Sonoran Flora from Acarospora).

Next, I will soon separate the Acarospora and work that one out, just need to find an apothecia with mature spores…

Check out the key to parasites toward the end of Sonoran Flora Vol. II
By: Jason Hollinger (jason)
2015-12-30 19:22:19 CST (-0500)

You’ll have to interpret it as the paraphyses (hamathecium) dissolving by maturity, and the spores as having one end attenuate to get to Endococcus_stigma. Neither looks right to me. But otherwise you end up in Polycoccum. There are possibilities there (see http://lichenicolous.net/) but we don’t have any descriptions of those species… Much work to be done in the lichenicolous fungi!

Of course there’s another theory!
By: J-Dar
2015-12-30 18:57:43 CST (-0500)

Doesn’t that ascus look like it has a lot of ascospores (ie: Acarospora)? I was confused by that too, but forgot to mention it. And yeah, that one apothecia amidst all the dark small ones was also weird. Another rabbit hole to dive into…

I’ve got another theory…
By: Jason Hollinger (jason)
2015-12-30 18:41:32 CST (-0500)

There are a few things that smell fishy about Placidiopsis:

1. the spores are dark(!)
2. there appears to be an actual Acarospora apothecium present in addition to the perithecia

3. the squamules are strongly verrucose and not overlapping at all, with a stipe-like attachment (instead of rhizohyphae)

So here’s another theory: Maybe it really is Acarospora, but heavily parasitized by Endococcus stigma. See how that works for you. I’m not 100% convinced, but I think it has potential.

Microscopy added, and long-winded commentary
By: J-Dar
2015-12-30 17:29:55 CST (-0500)

Jason, in regards to your comment, this appears to be a brown squamulose peretheciate lichen, and the black (dark grey actually) squamules are another species, which we will ignore for now.

Squamule with a thick stipe-like attachment, rhizines absent. One to several perethecia per squamule. Perethecia black, globose. Osteole black. Medulla mostly seemed filamentous. Upper cortex composed of globose cells below the epinecral layer.

Asci narrowly clavate. Ascoscpores uniseriate, 8 per ascus. Spores 1-septate, constricted at the septum, oblong, brown.

A few spore measurements are:
14.75 × 7.3 µm
15.3 × 7.6 µm
17.0 × 7.3 µm
16.4 × 9.8 µm
15.35 × 7.75 µm

I think the septate spores separate this specimen from Placidium, Clavascidium and Catapyrenium , which leaves (and keys well) Placidiopsis cinerascens. Unless we consider the spores have a pseudoseptum, which puts us in the part of the key where we could get to any of the previous genera.
Placidiopsis cinerascens is terricolous, however, and in California is known from serpentine soil. This specimen is from intruded rock with serpentinite, so not too far off.

By: Jason Hollinger (jason)
2015-12-10 11:34:46 CST (-0500)

Do you have a clear idea whether the black globular apothecia-like structures are associated with it or not? I could see this turning out to be a peritheciate species with some blackish secondary species scattered about.

Created: 2015-12-08 22:24:30 CST (-0500)
Last modified: 2015-12-31 20:47:49 CST (-0500)
Viewed: 119 times, last viewed: 2018-03-28 20:40:14 CDT (-0400)
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