Observation 202728: Heterodermia Trevisan

When: 2015-04-12

Collection location: DeSoto State Park, DeKalb Co., Alabama, USA [Click for map]

Who: Vitaly Charny (vcharny)

No specimen available

On a rock.

Proposed Names

14% (2)
Recognized by sight: lobulate deep apothecia, dark marginal cilia
56% (1)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
By: Jason Hollinger (jason)
2015-04-14 14:39:28 NZST (+1200)

Agreed, that these all look like the same species — nice population!

What you’re looking for is any coloration on the underside, especially near the tips, as well as a fibrous roughened texture. H. obscurata you certainly know well, with its conspicuously yellow/orange underside. But there are some more subtle variations: H. neglecta just has flecks of yellow pigment near the tip, but is otherwise white to grayish or brownish toward the interior; and H. casarettiana has a vaguely orangish-brownish coloration except maybe just white near the tips.

If the lower side is corticate (shiny, waxy-smooth), that is also very helpful, as only H. albicans, H. speciosa and H. pseudospeciosa have corticate lower surface. H. albicans you already know, it seems to have a distinctive appearance. But the rare H. pseudospeciosa doesn’t seem to differ too much from a rock-dwelling H. speciosa. Maybe that’s what you have here? But your photos look a lot like a rock-dwelling specimen of H. speciosa I have. (I did the K test to verify that it really is speciosa, despite the lack of conspicuous white cilia that species usually has.)

If the lower side is white and not corticate, on the other hand, you probably have H. japonica (or H. erecta if you’re in the mountains).

(Everything I know, by the way, comes from Lendemer. 2009. A synopsis of the lichen genus Heterodermia in eastern North America..)

By: Vitaly Charny (vcharny)
2015-04-14 14:10:03 NZST (+1200)

The thallus w/o apothecia on second picture. Looks like the same species.

I also add underside picture. Surface mostly whitish. As I see under microscope rhizines are pale, long, getting darker and shorter toward margins. Forked and unbranched. Few visible cilia are dark and forked like Brodo p.15a

And look closely at which thallus the apothecia belong to
By: Jason Hollinger (jason)
2015-04-14 08:41:04 NZST (+1200)

It would be entirely possible for two species of Heterodermia to be intermixed, but the apothecia (the ones I see) clearly belong to a sorediate thallus. So, while it’s always a rush to find fertile specimens of things like this, I think it’s clear in this case it’s “just” all the same sorediate thing (whatever that is).

By: Vitaly Charny (vcharny)
2015-04-14 08:10:21 NZST (+1200)

I am agreed – it has more different features from h.hypoleuca than similar… There was several talli on the rock and only one, most asymmetrical has apotheci. Will look closely at a specimen.

Don’t be fooled by a few apothecia!
By: Jason Hollinger (jason)
2015-04-14 07:02:35 NZST (+1200)

Sorediate species will occasionally produce apothecia, but fertile species will never produce soredia. There are abundant soredia on this specimen, so it must be one of the (many) soreediate species, not H. hypoleuca.

Created: 2015-04-14 06:14:25 NZST (+1200)
Last modified: 2015-04-14 14:02:25 NZST (+1200)
Viewed: 59 times, last viewed: 2017-06-20 18:13:49 NZST (+1200)
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