Observation 78268: Physconia venusta (Ach.) Poelt
When: 2011-09-24
Who: zaca
No herbarium specimen

Notes: A group of specimens growing on the same tree.

Images

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Details – Yet another specimen (left); Thallus very closely attached to the substrate (top right); detail to exhibit rhizines from upper lobes (bottom right).

Proposed Names

56% (1)
Recognized by sight: see comments

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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Recolecta
By: Anto (Antonio Valero)
2012-04-05 12:15:23 PDT (-0700)
Physconia distorta vs. Physconia venusta
By: zaca
2012-04-05 11:19:12 PDT (-0700)

After my previous comments and to further complicate this matter I checked the site of the Association Française de Lichénologie where there is a page dedicated to a variety of Physconia distortavar. subvenusta- in which at the margin of the apothecia small round lobules appear (link). This agrees with the recent comment of Antonio and reinforces the idea that for a full identification becomes necessary to observe all the details, including the underside. I’ll keep this in mind for future observations.

Got it, thanks guys!
By: Jason Hollinger (jason)
2012-04-05 11:17:54 PDT (-0700)
En cuanto a P. venusta
By: Anto (Antonio Valero)
2012-04-05 08:54:25 PDT (-0700)

la tengo recolectada el mes pasado sobre corteza de roble (de aspecto muy semejante) y con parte inferior de los lóbulos blanca, tal vez el centro a veces algo más ocre.
Pero P. distorta tiene la parte inferior siempre marrón oscuro o negro, incluso en los bordes.

Es cierto que P. distorta puede tener lobulitos en los apotecios, pero pienso que no tan marcados ni alargados como estos.

Un saludo
Antonio

Thanks, zaca
By: Jason Hollinger (jason)
2012-04-04 15:51:39 PDT (-0700)

You can’t trust everything you read! British Flora is apparently just wrong, or at very best misleading. I’ll make a note in my copy. Thanks for clearing this up for me.

I gave a look …
By: zaca
2012-04-04 15:26:21 PDT (-0700)

to the sites I use frequently: CNALH, Irish lichens, lastdragon, Timdal,
and in none of them the photos of Physconia distorta show lobules at margin of apothecia. The last one has the two species under discussion and see the difference.

I understand
By: Jason Hollinger (jason)
2012-04-04 14:53:51 PDT (-0700)

But P. distorta apparently can do that, too. From British Flora: “[apothecial] margin often with secondary lobules”.

So there is overlap between these two species. Both species can have black lower surface, lobulate apothecia and thallus, and both grow on bark but can sometimes grow on calcareous rocks. I can’t find any other differences in the descriptions of the two species.

I understood that …
By: zaca
2012-04-04 14:42:57 PDT (-0700)

the most distinctive is the part of the description mentioning “bords des lobes et rebord thallin des apothécies munis de proliférations foliacées ± développées”, which also appears in the remark: “facilement identifiable par les lobules ± développés qui garnissent le rebord thallin de l’apothécie”.

Okay, then obvious next question…
By: Jason Hollinger (jason)
2012-04-04 14:34:24 PDT (-0700)

How do you distinguish P. distorta from P. venusta ssp. subaquila? :)

British flora says P. distorta is epiphytic, but “occasionally on enriched limestones or stonework”. It also says P. distorta only “sometimes [has] secondary lobules in centre of thallus”. How do we determine saxicolous specimens with black lower surface and lobulate apothecia?

No need to answer, though, because your specimen is epiphytic, so it is not an issue here.

Quoting from the reference given,
By: zaca
2012-04-04 14:21:44 PDT (-0700)

there are two subspecies:
- Physconia venusta subsp. venusta, à face inférieure blanche (décrite ci-dessus)

- Physconia venusta subsp. subaquila, à face inférieure noire et plutôt saxicole.

How do you distinguish the two species?
By: Jason Hollinger (jason)
2012-04-04 14:12:52 PDT (-0700)

Lower surface is entirely white in P. venusta, black toward center in P. distorta?

Ok
By: Anto (Antonio Valero)
2012-04-04 13:55:37 PDT (-0700)

ok, puede ser Physcia venusta

Face inférieure blanche?

Physconia venusta?
By: zaca
2012-04-04 13:20:41 PDT (-0700)

I just saw the description and the photos given in ac-lille for the species Physconia venusta and it seems to me that it is a better option for the classification of this specimen.

RE: aff. Physconia distorta
By: zaca
2012-02-27 02:01:08 PST (-0800)

Gracias, Antonio, for your opinion.

aff. Physconia distorta
By: Anto (Antonio Valero)
2012-02-26 04:16:30 PST (-0800)

A mí tambien me parece más Physconia distorta que Physconia grisea, no veo soredios ni isidios y las rizinas pienso que no todas son simples.

Saludos
Antonio

No one has to know …
By: zaca
2011-10-08 15:45:28 PDT (-0700)

the exceptions to the characteristics of some genera, unless he needs. For this genus it was pointed out in the refrence and also in Irish lichen. If I understood well, definetely this is not P. grisea and can be _P. distorta.
Thanks, Jason, for you comments.

Showing my ignorance…
By: Jason Hollinger (jason)
2011-10-08 14:45:10 PDT (-0700)

Here I thought all Physconia had bottle-brush-like rhizines! Seems there has to be an exception to every rule. :)

According to my (North American!) concept of the genus, lobules such as you see in these specimens are very significant. There are other genera, like Peltigera and Nephroma where just about any species can become lobulate given the right conditions. Not so in (North American) _Physconia. Likewise, the lack of soredia. Even young specimens should have at least some soredia, and these definitely are not young specimens.

In fact,
By: zaca
2011-10-08 13:40:32 PDT (-0700)

If soredia exists, and I’m not sure about their existence, it is confined to some of the lobe tips. On the other hand, the rhizines I could see do not seem to be “bottle-brushed”. That’s why I proposed P. grisea. These specimens seem to be different from the one in MO, but this can be a question of maturity.

There are all European species, so what do I know?
By: Jason Hollinger (jason)
2011-10-08 11:03:29 PDT (-0700)

But these specimens all have phyllidia not soredia. They look more like P. distorta than P. grisea.

Created: 2011-10-08 07:11:53 PDT (-0700)
Last modified: 2012-04-04 16:45:18 PDT (-0700)
Viewed: 411 times, last viewed: 2016-11-26 04:03:34 PST (-0800)
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