Echinomastus spines

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bruno
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Post by bruno »

thank you Peter :D
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iann
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Post by iann »

Yes, that's the one I mentioned, but it doesn't really have much to say about Echinomastus.
--ian
peterb
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Post by peterb »

I thought the paragraph on Echinomastus erectocentrus and johnsonii was significant, actually.

"If monophyly is the sole criterion for generic circumscription, then the inclusion or exclusion (in Sclerocactus) of Echinomastus is a subjective decision."

However, it is disappointing that other members of the genus were not sampled. I've often thought that Echinomastus erectocentrus, acunensis and johnsonii were closest to Sclerocactus. The Chihuahuan species currently in Echinomastus are not as close to Sclerocactus, IMO. Since I am basing my opinion only on gross morphology, I could of course be dead wrong. But I'd love to see cladograms investigating the position of the Chihuahuan Echinomastus relative to Turbinicarpus/Neolloydia/Glandulicactus etc.

I don't think the Echinomastus group (including all the Chihuahuan forms) will hold up as monophyletic, ultimately. E, mariposensis seems very distantly related to E. johnsonii, for example.

I hope Butterworth or someone is doing some research on the Echinomastus bunch. Meanwhile, creating a large probably polyphyletic smorgasbord genus, "Sclerocactus" in the sense of Hunt and Taylor, really has not been an improvement.

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iann
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Post by iann »

Agreed. I see too many sweeping statements made on the basis of just one or two sampled species. In particular when only one species is sampled it is necessarily impossible to determine whether the genus is monophyletic, and you have more or less the same problem if you take samples from two species you are already sure are very close. The next sample might end up right next to Navajoa or somewhere else completely.

Neolloydia sl is embedded in Mammillaria and I don't think any Echinomastus is going to go there. Glandulicactus is likewise well-defined but not close to Sclerocactus. I suppose an Echinomastus could show up there but the morphological differences suggest not. Maybe one of the ones with nectaries? Turbinicarpus always shows up in a loose group with Pediocactus, Epithelantha, and Ariocarpus (including Strombocactus), so not really promising country for Echinomastus. I would have thought the real question was whether and how it might overlap with Sclerocactus or remain separate (or at least separable).
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peterb
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Post by peterb »

Yes, I agree that is the real question, but I see plants like unguispinus and mariposensis as pretty far from erectocentrus/johnsonii and Sclerocactus ss. Maybe erectocentrus and johnsonii will end up in Sclerocactus but the Chihuahuan Echinomastus will stay separate. Anyway I hope to see some solid research on this sometime during my lifetime. :-)

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bruno
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Post by bruno »

yes it would be great seeing a cladogram for a wider sample of taxa which we feel are or can be close to Echinomastus.

From what I understand, dna numbers in Porter' s article strongly support including Toumeya in Sclerocactus while inclusion of E. erectocentrus and johnsonii in Sclerocactus would make the group polyphiletic and is therefore not supported.

I am now missing the reason why Hunt and Taylor did decide to merge Echinomastus and other genera into Sclerocactus giving raise to a clearly polyphiletic group and to the proliferation of new names. Do you know/have access to that piece of literature?

Another point I have is related to Echinomastus gautii, is it acceptable to name a species from an herbarium specimen without any link to a living population? Is this name valid?

Coming back to spines let' s talk about mariposensis.

When young spines con be somewhat similar to certain forms of warnockii, the two species sharing most of their range but live in different habitats and apparently do not interbreed.

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Adult plants cannot be confused with any other Echinomastus species

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This is a taxon known as hispidus (sb452), seeds are now classified as 'mariposensis sb452' by some Czech seller

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another sb452

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This is then E. erectocentrus sb462, with almost appressed spines

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while this Erectocentrus comes withouth fn and a quite different look

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This should be acunensis sb146 from Sonoita, Sonora

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Last, as already discussed in another post, seedlings of johnsonii and lutescens are also very different

johnsonii

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lutescens

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I am sorry I don' t have adult specimens of johnsonii and erectocentrus to add :wink: :)
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bruno
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Post by bruno »

btw warnockii kakui with buds today

Image

:wink:
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Post by iann »

dna numbers in Porter' s article strongly support including Toumeya in Sclerocactus while inclusion of E. erectocentrus and johnsonii in Sclerocactus would make the group polyphiletic and is therefore not supported.
No, the study certainly didn't show that the inclusion of those two Echinomastus species would render Sclerocactus polyphyletic. It showed that the exclusion of Toumeya would render Sclerocactus paraphyletic, and that's its inclusion was strongly supported. The data did not clearly indicate whether Echinomastus should be included in Sclerocactus or not. It showed that Echinomastus, those two species at least, shared most recent ancestors with Sclerocactus, including two key sequence deletions, but was probably a sister group to all other Sclerocactus. Sampling only two species and very few outgroups meant that it wasn't possible to make strong statements about Echinomastus.

I don't have any of Hunt's papers on Echinomastus/Sclerocactus but it is no surprise that he would choose to place two morphologically similar groups into a single monophyletic genus. As I understand, the main difference is the degree of extension of the areole into a short groove, the groove being longer in Echinomastus and shorter in Sclerocactus? I'm not sure what the difference is for Ancistrocactus: indehiscent fruit? That would make sense for why Glandulicactus and Ancistrocactus have often been placed together. In that respect, Echinomastus fruit seems to be all over the place, some indehiscent, some dehiscent longitudinally, and some dehiscent basally.
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Post by peterb »

Those are beautiful plants, Bruno! It's great to see people propagating johnsonii and 'lutescens'. Very few propagate Echinomastus at all, and erectocentrus and johnsonii are considered to be "impossible." Perhaps we are making some progress? I hope so.

The SB452 is closer to warnockii, not mariposensis, at least according to the authors of the species. It was sold by Brack as "aff. warnockii, Cuatrocienegas" for a long time.

Re: taxonomy. Porter and I have been in email correspondence but he hasn't yet let me know what I can quote from this discussion and what he would prefer I do not quote. This is of course a sensitive issue as, once a scientist's name gets affixed to a particular opinion, it can be hard to shake it later when there is an actual publication of results.

Anyway, I don't think the group of plants we call "Echinomastus" and which were placed in Sclerocactus are monophyletic. So I think the reality is actually much messier than just keeping Echinomastus separate. To what degree the taxonomy ought to reflect this messiness is another question. But I would not be surprised to hear that the Chihuahuan plants are not monophyletic with johnsonii/erectocentrus. And I wouldn't be surprised to hear that they are and that Sclerocactus belongs within Echinomastus. And there's probably some other possibility I'm not even considering that *also* wouldn't surprise me. :-)

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bruno
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Post by bruno »

iann wrote: No, the study certainly didn't show that the inclusion of those two Echinomastus species would render Sclerocactus polyphyletic. It showed that the exclusion of Toumeya would render Sclerocactus paraphyletic, and that's its inclusion was strongly supported. The data did not clearly indicate whether Echinomastus should be included in Sclerocactus or not...
thank you for the clarification Ian, I am not used to such scientific terms but after reading Porter' s paper with more attention I think I understand your point. It is however confusing that Anderson reports (under the treatment of Sclerocactus pag. 625) that in his paper of 1994 Porter "...defined the genus rather narrowly, excluding the species placed in the genera Ancistrocactus, Echinomastus, Glandulicactus and Toumeya (!!)". This paper is however not mentioned among the literature cited in his book. Anderson also refers to a more recent work from Porter in 1999 (the CCI we miss) where "based on dna sequencing and morphological data ..... Sclerocactus .... should be subdivided and Echinomastus recognized as a distinct genus".

Thank you Peter, it is perhaps to early to understand if there is actually a progress in growing these plants. I am curious to see the impact of winter waterings on their grow rate, given that seeing them all still alive is encouraging in itself.

SB452 is kind of a puzzle, and I would love to learn more about its relationship with the other taxa but finding something in the literature looks like a difficult task.

Nice to hear that Porter is working on this, don' t see the hour to read something more on his research.

I am also wondering about "the other possibilities" that wouldn' t surprise you :)
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Post by peterb »

By the "other possibilities," I guess I just meant that there is a whole group of plants that seem morphologically distinct *enough* but perhaps not to be recognized at the taxonomic level, at least not from the point of view of systematics alone. Ancistrocactus, Glandulicactus, Thelocactus bicolor and company, Echinomastus, Sclerocactus, Neolloydia, Hamatocactus, Toumeya, Navajoa all seem to pose a puzzling matrix of close relationship yet enough phenetic distinction for the names to still be in wide use. The boundary lines between these genera are like obscenity: we know it when we see it. :-)

I feel safe in relaying that Porter currently feels that Anderson *misinterpreted Porter's data*, and that Sclerocactus and Echinomastus are indeed congeneric. But I don't have anything else to go on at this point, including the original data itself, supposedly published in 1999 but still not at hand.

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iann
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Post by iann »

This is all very unsatisfactory. I see several authors referencing other works incorrectly, quoting other authors out of context, and hence ultimately presenting simple opinion as proven fact.
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peterb
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Post by peterb »

I agree. It surprises me that Anderson may have in fact cited a work that was never published and included an interpretation at odds with the original researcher. I'm sure these things happen more often than we realize, as we usually don't have time to go back to the primary data, let alone email the cited scientist personally.

I have felt a similar frustration in the publication of many "naturally occurring hybrids," for example, without due diligence and convincing data. I have also felt that the finer distinctions in taxonomy are often stated as proven fact when many of these conclusions are opinion. Admittedly, well informed and highly educated opinion, but opinion nonetheless. The opinions don't rankle me, but the attitude of authoritative hard science in an area that is still highly fuzzy definitely does.

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