New Selenipedium species described.

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PaphMadMan

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The pouch has reverted to a form similar to the petals. Phrag lindenii is another example of this. It could be a pretty small genetic difference, just disrupt one developmental gene perhaps. In that environment it must lead to more efficient pollination by a different pollinator or it wouldn't have become established.
 

Rob Zuiderwijk

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@Tom: In the text they speak of 8 other specimen next to the holotype that they studied between 2001 and 2015.
They also say that until now they where unable to find any other population(s), and that the habitat it grows in is very rare indeed.


And further, in all aspects this looks to me like a peloric taxon. From the description it is clear that the pouch shaped lip is replaced by a petal like lip. the synsepalum is split into two separate petals (or more correct: The two petals are not fused into a synsepalum) and there are three fertile anthers instead of two.
So in appearance a throw back to a lily like ancestor.

All in all and interesting discovery.


Rob.
 
D

Drorchid

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@Tom: In the text they speak of 8 other specimen next to the holotype that they studied between 2001 and 2015.
They also say that until now they where unable to find any other population(s), and that the habitat it grows in is very rare indeed.


And further, in all aspects this looks to me like a peloric taxon. From the description it is clear that the pouch shaped lip is replaced by a petal like lip. the synsepalum is split into two separate petals (or more correct: The two petals are not fused into a synsepalum) and there are three fertile anthers instead of two.
So in appearance a throw back to a lily like ancestor.


All in all and interesting discovery.


Rob.
Definitely a very interesting species! This species might be the most primitive or "ancestral" of all the lady slippers, and may have changed the least compared to any other lady slipper species. At one point the common ancestor of all lady slippers did have 3 anthers, 3 sepals, and 3 petals. I think the genus Selenipedium in general looks more ancestral than any other lady slipper genus. It would be interesting to do a DNA experiment to determine which species are more "ancient".

I think when you look at Phrag. lindenii, this is a reverse mutation, and probably at one point it's ancestor looked more like Phrag. wallisii (aka warscewiczianum).

Ok this is my Hypothesis regarding how the different Lady Slipper Genera are related and evolved. At one point I noticed that some Cypripedium species, native to Mexico, like Cyp. irapeanum, look like they may be "intermediate" and more closely related to Selenipedium. Also, when you look at the other side of the world, some species of Paphiopedilum, like Paph. micranthum and Paph. armeniacum look like they are more closely related to Cypripediums. This gave me the following idea:

I think at one point in time the common ancestor of all lady slippers originated in what is now South America, and was something that looked like this new species Selenipedium chironianum. Just like it's lily ancestors, it had 3 anthers, 3 sepals and 3 petals, of which one petal was starting to morph, and become a little more differently shaped compared to it's "sister" petals. from this ancestral type, other species of Selenipedium evolved. The third petal of these species kept evolving, and slowly turned into what we call a "pouch". It was probably an evolutionary advantage to attract (or trap) their pollinators, and thus have more off-spring. Also, over time the two lower sepals joined into what we now call the "synsepal". And finally, instead of having 3 anthers, the new species evolved with having only 2 anthers. The third anther actually morphed into what we now call the "staminodal shield". Eventually from some common ancestor that probably looked like some extinct Selenipedium species, populations got isolated, and over time evolved into the related genus "Phragmipedium". This new genus furthur evolved and spread throughout South and Central America. Populations of Selenipedium that were further north evolved into species that looked more like the modern day Cyp. irapeanum, and these ancestral Cypripedium species formed the ancestors of the new genus Cypripedium. This new genus spread and evolved all over the Northern Hemisphere, and eventually reached Asia and Europe. When they reached the tropical parts of China, again they were separated long enough that they evolved into a new genus: Paphiopedilum, of which I think the parvisepalums (like Paph. armeniacum and Paph. micranthum) are probably the most closely related to Cypripediums...From China they spread throughout all of South East Asia, India, and all the islands of Indonesia and the Philippines to evolve into all the different Paph. species.

Anyway that is my hypothesis of Lady Slipper Evolution in a nut shell. Now we need to prove it :)

Btw, if you ask me what is the most "ancestral" Phragmipedium species, I would probably say that it is something that would look like Phrag. sargentianum.

Robert
 

PaphMadMan

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Interesting hypotheses Robert. There are at least a dozen doctoral theses in the evolutionary scheme you suggest, but sticking to this species I think it is far more likely that it had a more typical Selenipedium ancestor and lost the specialized (slipper) orchid characteristics. I haven't read the whole paper yet, my French isn't good enough to make it a casual read, but the authors describe it as a close relative of Selenipedium palmifolium which doesn't seem consistent with it being a primitive relict form. And if it were it would probably have to be considered a new genus.

Almost all orchids have a relationship with a single species or small range of pollinators. The changes here wouldn't be surprising if a population got isolated away from the specialized pollinators and had to adapt to whatever generalized pollinators were available, especially if any pollinators were rare in that environment.

Anyway, that's my hypothesis. Now, who wants to fund the research?
 
D

Drorchid

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Interesting hypotheses Robert. There are at least a dozen doctoral theses in the evolutionary scheme you suggest, but sticking to this species I think it is far more likely that it had a more typical Selenipedium ancestor and lost the specialized (slipper) orchid characteristics. I haven't read the whole paper yet, my French isn't good enough to make it a casual read, but the authors describe it as a close relative of Selenipedium palmifolium which doesn't seem consistent with it being a primitive relict form. And if it were it would probably have to be considered a new genus.

Almost all orchids have a relationship with a single species or small range of pollinators. The changes here wouldn't be surprising if a population got isolated away from the specialized pollinators and had to adapt to whatever generalized pollinators were available, especially if any pollinators were rare in that environment.

Anyway, that's my hypothesis. Now, who wants to fund the research?
LOL, we should do a joint research!

btw, This new species has 3 characteristics that are considered more "primitive":
- having 3 petals (and no pouch)
- having 3 anthers (instead of two)
- having 3 sepals (rather than a dorsal sepal and a fused synsepal)

The chance of having 3 reversed mutations i.e going back to it's ancestral type seem very small and unlikely. I learned early on that if you have two hypotheses that the most simple one, is often (but not always) correct.

Our hypotheses are:

#1 ancestral type which had 3 anthers, no pouch, and 3 sepals evolved into a species with a pouch, two anthers, and a synsepal. This species evolved again into the species Selenipedium chironianum which had reverted back to not having a pouch, having 3 anthers, and 3 sepals.

# 2 ancestral type evolved into Selenipedium chironianum, still having 3 anthers, no pouch, and 3 sepals.

To me Hypothesis #2 seems the most simple and most likely one.

So, the question is how do we prove Hypothesis #1 is correct or Hypothesis # 2 is correct?



Robert
 

naoki

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Robert, you might be interested in this relatively recent paper:

Guo Y-Y, Luo Y-B, Liu Z-J, Wang X-Q (2012) Evolution and Biogeography of the Slipper Orchids: Eocene Vicariance of the Conduplicate Genera in the Old and New World Tropics. PLoS ONE 7(6): e38788.

Code:
             --Paphiopedilum
          __/
     ____/  \--Phragmipedium
 _ _/     \----Mexipedium
/    \---------Selenipedium
\--------------Cypripedium
But the support for the branch grouping everything except Cypripedium appears to be not as strong as the other branches.

Also, I thought that there were several other orchid groups which diverged within Orchidaceae before Cypripedioideae. I'm not sure if they have column/pollinia structure, though.
 
D

Drorchid

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Thanks Naoki! That was an interesting paper! Well, according to their paper, the genus Cypripedium is most ancestral, followed by Selenipedium. Phrags, Mexipedium and Paphs are the most advanced. Also what I found was interesting is that within the Cypripediums, the Mexican species including Cyp. irapeanum were the most primitive, which can explain why they show similarities with Selenipedium.

Robert
 

Rob Zuiderwijk

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Robert, you might be interested in this relatively recent paper:

Guo Y-Y, Luo Y-B, Liu Z-J, Wang X-Q (2012) Evolution and Biogeography of the Slipper Orchids: Eocene Vicariance of the Conduplicate Genera in the Old and New World Tropics. PLoS ONE 7(6): e38788.

Code:
             --Phragmipedium
          __/
     ____/  \--Mexipedium
 _ _/     \----Paphiopedilum
/    \---------Selenipedium
\--------------Cypripedium
But the support for the branch grouping everything except Cypripedium appears to be not as strong as the other branches.

Also, I thought that there were several other orchid groups which diverged within Orchidaceae before Cypripedioideae. I'm not sure if they have column/pollinia structure, though.
No offence, but I think you made a mistake in the branch graphic (cladogram). Paphiopedilum and Mexipedium/Phragmipedium should switch place. I changed it in the quoted text in this message.

Rob
 
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polyantha

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No offence, but I think you made a mistake in the branch graphic. Paphiopedilum and Mexipedium/Phragmipedium should switch place. I changed it in the quoted text in this message.

Rob
Yes, I was thinking the same. An interesting new species, but very ugly in my eyes. one could argue that P. ooii is ugly too, but actually I like that paph. Crazy orchid world where we sometimes cannot explain why we like some plants and others not...
 
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