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I think that the colors observed from the section are “more or less” according to the description. But, I will try to look at the spores in a forthcoming oportunity.
According to the Sonoran Flora (Nash et al. 2004): Spores are 8 per ascus, hyaline, simple, ellipsoid, 10-14 × 6-8 µm. Upper cortex should be K+ yellow, all else negative. Epihymenium should be dark red-violet to red-brown; hymenium violet-red or brown above; hypothecium dark brown to yellow-brown. The margin of the apothecia can be either biatorine or lecanorine (presumably explaining the apparent lack of algae in your section).
A good way to be sure you’re looking at a spore is if you see a few together — no other microstructures will be so regularly-shaped and
sized. If you furthermore see them grouped together in an ascus, there’s no question. You can flood the section with KOH and squash it to help separate the sterile tissue in the hymenium from the asci and spores. A friend also noted that rock crusts regularly produce far fewer spores than crusts on trees, soil or moss - it is entirely plausible (although unlikely) that there’s not a single mature spore in your entire section.
The brown hymenium and dark brown hypothecium are uncommon, at least among lecanorine crusts. I can’t find any spores in your photos, which probably means that they are small and colorless, which also supports Tephromela.
confirm this guess in the near future. Thanks, Jason, for the information on how two distinguish between genera.
I’ve only seen T. atra on bark. I didn’t realize it looks so contorted on rock, and I think that is supposed to be the more common habitat.
But the only way to be 100% sure, even for most professional lichenologists, is to use microscope. In this case spores alone should be enough to give you genus:
(Oh yes, Brodo confirms that T. atra has a thinner thallus on bark. I believe there is work being done on this species as we speak.)
about considering the genus Rinodina. But, at the end, all I can say is that is one more possibility to add to the two mentioned initially. In fact, I think that without chemical and/or microscope analysis it is not possible to go further.
It seems that in my specimen the thallus is all it twisted and the cup-like forms with a dark center are almost all of them immersed in the thallus and are bent upon themselves, so to speak. Below I give three examples of species which, by decreasing other of similitude, I think that are analogous to my specimen:
-Tephromela atra: see a description and some pictures here; and the most similar picture I found HERE (there is a big gallery of this species);
- Diphoschistes muscorum: see a picture here (see also picture 16);
- Rinodina exigua: see a picture here.
I’m not quite sure about the place where I took the picture to the specimen but, if I will find it again, I will perform the K,C, and KC tests to begin and collect a sample for further analysis.
Created: 2010-07-04 19:48:17 CEST (+0200)
Last modified: 2010-08-14 20:38:44 CEST (+0200)
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