Royal Fern family, discussing systematics, nomenclature and hybrids within

I liked to proceed an ongoing, interesting discussion concerning Royal Ferns, Ophioglossum in wide sense, reported hybrids within and a newly published allo-tetraploid species found in SE Asia. You may find it at observation Observation 25993646 plus lesser part at Observation27673795

I liked to proceed this here at iNatForum, but no longer directly at observations, for that purpose i will copy gathered comments upon both observations to here, there are less contributions at latter observation. Don’t know if there was another, smarter chance to move discussions from observations directly to forum items.

1st. part of contributions to Observation 25993646:

Malte @mwtreftig added an ID as: Claytosmunda claytoniana and commented: Osmunda claytoniana at Wikipedia

The Paraphyly of Osmunda is Confirmed by Phylogenetic Analyses of Seven
Plastid Loci. Author(s): Jordan S. Metzgar, Judith E. Skog, Elizabeth A. Zimmer, and Kathleen M. Pryer. Source: Systematic Botany, 33(1):31-36.:
We also resolve subgeneric relationships within Osmunda s.s. and find that subg. Claytosmunda is strongly supported as sister to the rest of Osmunda.

A community‐derived classification for extant lycophytes and ferns PPG I

H. Order Osmundales Link, Hort. Berol.: 445. 1833. Circumscription sensu Smith et al. (2006b). Order consists of one family. One family, six genera, and an estimated 18 species.

Family Osmundaceae Martinov, Tekhno‐Bot. Slovar.: 445. 1820. Circumscription sensu Smith et al. (2006b). Monophyletic (Yatabe et al., 1999; Schuettpelz & Pryer, 2007; Metzgar et al., 2008). Six genera and an estimated 18 species.

Claytosmunda (Y.Yatabe, N.Murak. & K.Iwats.) Metzgar & Rouhan, this classification (see below). Type: Claytosmunda claytoniana (L.) Metzgar & Rouhan (≡ Osmunda claytoniana L.). Circumscription equivalent to Osmunda subgenus Claytosmunda in Yatabe et al. (2005). Monotypic.

Burkhard @burkhard_plache added ID as: Claytosmunda claytoniana

Erwin @erwin_pteridophilos commented:
@mwtreftig Malte you surely know this hybrid https://www.inaturalist.org/observations/1817991 would be declared as intergeneric by changing one parent to Claytosmunda, and intergeneric hybrids are the most exceptional, questioning separation of genera. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500836

Malte answered:
@erwin_pteridophilos you have a point!! I was not aware of this consequence of splitting the genus. You should send this to Eric Schüttpelz as coordinator of PPG-1

@erwin_pteridophilos …but see: it happens anyway… https://phys.org/news/2015-03-million-years-fern-genera-hybrid.html

Erwin responded:
@mwtreftig indeed Malte @crothfels & al.'s published intergeneric hybrid × Cystocarpium roskamianum is a most exceptional, inexpected one!
By that proving true the existence of rarely happening natural crossings of clearly, yet distant genera. Natural hybridization between genera that diverged from each other approximately 60 million years ago
Separating Claytosmunda from Osmunda raises the question how wide or narrow generic concepts shall be at all to be useful, and to achieve monophyletic units at best. So we got stronger or weaker subjective preferrences of unition or splitting in general, there is simply no calculable “right or wrong” value.

By the way, as commented upon https://www.inaturalist.org/flags/371238 there is the issue of appropriate intergeneric hybrid name. Christopher @choess mentioned it “would have to be something ghastly like Osmundclaytosmunda x ruggii”.
I proposed perhaps better sounding and useful combinations as “Hybridosmunda × ruggii” or “Mix(k)tosmunda × ruggii” (not sure if “×” needed to be placed in front of genushybrid?). Tyi @crothfels

Christopher @choess answered:
This is governed by the Code, Art. H.6.2: “The nothogeneric name of a bigeneric hybrid is a condensed formula in which the names adopted for the parental genera are combined into a single word, using the first part or the whole of one, the last part or the whole of the other (but not the whole of both) and, optionally, a connecting vowel.”

Erwin wrote:
However, i do prefer personal freedom of people, hence do reject superfluous regulations, or to regard any likewise codes as ultimate laws anyone who liked to publish new combinations had to follow, as otherwise names were treated as “invalid”.
I won’t publish intergeneric hybrids, yet this article of nomenclatural code is nothing but suggestive to me and i surely don’t need judges for that purpose.
Sure, useful rules where essential, but not as forcing end in itself when leading to unspell- and readable miscreation of names.

End of part 1 of the whole conversation, the rest is going to follow.

Best regards to all, Erwin

Part 2 of the whole current conversation upon Observation 25993646

Carl @crothfels commented:
Very interesting discussion, thanks all. I was say that personally the Osmundaceae treatment was one of the more controversial decisions in PPG1 – it’s basically a lumping/splitting decision, so one can go either way and still have monophyletic genera. The main motivation was to recognize the deep evolutionary isolation of these groups, but yes, that is undermined by the intergeneric hybrid. I would love to see that hybrid confirmed with genetic tools, BTW. As for its name, how about xClaytosmundada?

Christopher @choess answered:
Well, in a world with xCystocarpium, anything is possible. My dislike is mostly a file clerk’s pique for leaving loose ends dangling, in this case O. x ruggii. (And in retrospect, it might have been better to adopt a different name at genus level–Art. 11.2, no priority at a different rank.)

Splitting into a bunch of small (extant) genera is definitely going to get some flak, but maybe sometimes that’s just the way it is–patterns in nature are not always shaped to our convenience. (cf. your latest installment of the War On Notholaenids).

Perhaps a touch of Dada here is exactly what is needed. ;)

Erwin @erwin_pteridophilos answered:
Do you know about reliable evidence for existing hybrid Osmundastrum cinnamomeum × [Clayt]Osmunda claytonia @dalea @donlubin @milopyne @crothfels @choess @jsmetzgar @mwtreftig ?

My last naming suggestions in (nearby) agreement with the Code Art. H.6.2 are:
“× Osmundoclaytos” (respectively “× Osmundoclayton” or “× Osmundoclayta”), so we may be curious for the decision at last, not my turn.

Carl @crothfels answered:
@erwin_pteridophilos – no, I don’t know of any evidence for a hybrid involving Osmundastrum (and one would be very surprising - even more so than the Osmunda/Claytosmunda hybrid – given Osmundastrum’s deep isolation)

Erwin @erwin_pteridophilos wrote:
Thanks for response and your estimation @crothfels !
@donlubin please see comments above, perhaps partially answering your questions.

Malte commented:
https://www.researchgate.net/publication/233486608_A_New_Allotetraploid_Species_of_Osmunda_Osmundaceae

https://www.researchgate.net/publication/272079440_Are_the_genomes_of_royal_ferns_really_frozen_in_time_Evidence_for_coinciding_genome_stability_and_limited_evolvability_in_the_royal_ferns

to start with…

Donlubin @donlubin commented:
Several specimens came through the herbarium at Harvard University that were labeled O. cinnamomea x claytoniana. One was probably just O. claytoniana. But one looked like it could be that hybrid. We sent it to Japan for confirmation, and have not yet heard back.

Erwin responded:
Thanks a lot for linking to publication of the newly detected kind of Royal Fern, Malte!

So we got to recon now with 4 different hybrids within Osmunda in wide sense, and this hybrigogenous 4-ploid O. hybrida.
For sure there will have been the initial hybrid between O. regalis (s.l) from India and O. japonica, still not known at recent time.
Hybrid Osmunda × intermedia is apparently the only recent one within O. in strict sense, respectively subgenus Osmunda.
O. × ruggii from E North America, and O. × nipponica from Japan are hybrids between [sub]genus Osmunda and Claytosmunda, hence needed newly invented intergeneric name combination in case parental species’ belonged to different genera, see discussion above.
The same with O. × mildei whose ancestors belong to [sub]genus Osmunda and Plenasium, still here the combination “× Plenosmunda” looks well done to me.

As Carl mentioned before, Osmundastrum is phylogenetically far remote from the rest of the family, hence hybrids seem to be the most unlikely.
The easiest and convincing explanation for seemingly intermediate plants is there general similar appearance, in especial with sterile ferns.
Yet i may imagine that aberrations of fertile leaves do occur which could look like intermediate hybrids.
@donlubin Don, i do suppose those specimen from Harvard University had not been analyzed and sequenced by the authors of the above linked new publication?

Malte @mwtreftig commented:
https://www.biorxiv.org/content/10.1101/005777v1.full.pdf
https://www.biorxiv.org/content/10.1101/005777v1.full
another one…

Christopher @choess answered:
Yeah, that Bomfleur work is really cool. I was very impressed by the PeerJ paper harmonizing the present-day taxonomy with fossil evidence. Thanks for bringing O. x nipponica to my attention–I wasn’t aware of this additional intergeneric hybrid.

Fraser-Jenkins does lay some stress on the occasional occurrence of mutant forms in O. japonica which are hemidimorphic rather than holodimorphic, leading to confusion with O. regalis. (See his “Annotated Checklist” part 1 and comment at https://sites.google.com/site/efloraofindia/species--ferns/m---z/o/osmundaceae/osmunda/osmunda-hugeliana; tanquam ex ungue leonem.)

Does anyone know of a more recent treatment of the O. regalis complex than Bobrov 1967? I’d like to feel more confident morphologically separating O. regalis s.s. from O. spectabilis, and Fraser-Jenkins clearly believes the difference is more than cladistic.

And thanks also to @jsmetzgar, who really got the ball rolling on phylogenetics in this group!

End of part 2 of the whole conversation, the rest is going to follow.

Part 3 of the whole current conversation upon Observation 25993646

Carl @crothfels commented:
yowzahs. A guy steps away from this thread for a bit and there’s all this new discussion! Very cool. Quickly, though – I’m pretty sure that Claytosmunda is monotypic – just Claytosmunda claytoniana. The hybrid xnipponica is a within-Osmunda hybrid, I believe (one of its parents might have been treated in subgenus Claytosmunda, but turns out that it’s actually an Osmunda rather than being allied with C.claytoniana)

Malte Malte W. Treftig commented:
https://www.academia.edu/11602214/Using_more_than_the_oldest_fossils_dating_Osmundaceae_with_three_Bayesian_clock_approaches
just an addition…

https://www.degruyter.com/downloadpdf/j/acpa.2018.58.issue-2/acpa-2018-0014/acpa-2018-0014.pdf
news from the upper Triassic …

Erwin @erwin_pteridophilos responded:

THANKS A LOT to all participants of this long, ongoing dicussion concerning family Osmundaceae and hybrids within !! @mwtreftig @burkhard_plache @choess @crothfels @donlubin
I do suggest to move the conversation to https://forum.inaturalist.org/c/nature-talk/18 as topic to be proceeded, but do assume this could just be done by manual copy and paste?

I could not take up all information added as comments and at linked sources so far, will try to do so later on in best case.
See latest 2 comments at https://www.inaturalist.org/observations/27673795

Christopher @choess :
Klekowski reportedly produced one in culture in the 1970s: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.963.1223&rep=rep1&type=pdf

Erwin @erwin_pteridophilos:
Thanks @choess such experiments, and the fact Klekowski could produce differently mixed hybrids between Osmunda regalis (var. spectabilis), O. (s.l.) claytoniana and Osmundastrum cinnamomeum, is the most surprising and interesting!

To summarize hybrid results:
O. claytoniana × O. cinnamomeum, IB5-12 × OC1: 1 Sporophyte
O. regalis (spectabilis) × O. cinnamomeum, CON28 × OC2: 1 Sp., HB5 × OC7: 2 Sp.,
together = 3 Sporophytes
O. regalis (spectabilis) × claytoniana, IB5-8 × HB5: 1 Sporophyte

I didn’t yet read what happened with resulted hybrid sporophytes later on, if these survived at all, or might have grown to mature ferns?
For sure we may not prove true if Klekowski’s sporophytes had been of mixed specific origin or not, so it was useful to repeat likewise crossing experiments.
But doing so means a lot of effort as i may imagine!

Carl, @crothfels i surely know nothing about O. × nipponica, have just read for the first time about this kind of hybrid.

However, Claytosmunda claytoniana [var. / ssp. pilosa] is native to E Asia inclusive Japan, hence there might be chances to cross with O. japonica.
The two member of [sub]genus Osmunda in Japan are said to be O. japonica and close allied O. lancea, thus the only possible hybrid was yet named as O. × intermedia.
We will see what O. × nipponica turns out to represent.

Best regards, Erwin

Last part no. 4 of the whole conversation, a short rest commented upon Observation 27673795

Tom Diggs added ID as Claytosmunda claytoniana

Erwin @erwin_pteridophilos commented:
@dalea @donlubin you surely know this hybrid
https://www.inaturalist.org/observations/1817991 would be declared as intergeneric by changing one parent to Claytosmunda, and intergeneric hybrids are the most exceptional, questioning separation of genera.
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500836
See as well discussion at Observation 25993646

Donlubin answered:
I’d be happy to call all three species Osmunda. I believe I have seen a hybrid between Interrupted and Cinnamon ferns. I mostly agree with the ID and don’t contradict about the nomenclature.

Erwin @erwin_pteridophilos responded:
@donlubin as far as i know (what is relatively little!) hybrids between Interrupted and Cinnamon Fern have never been proved true. Hence both hybrids Osmunda (s.l.) × ruggii and O. × intermedia in Japan are told to be the only ones in their family.
O. mildei representing a (fertile: much likely wrong!) fern in SE China is thought to be of hybrid origin from O. japonica and O. angustifolia or O. vachellii, don’t know if definitely allo-polyploid or not. Tyi @choess

Donlubin answered:
There were a couple of specimens labeled O. cinnamomea x clintoniana that came through the Harvard herbarium. One looked convincing, and was sent to Japan for confirmation. I haven’t heard about it since.

Erwin wrote:
Haha, perhaps this fern “Howevernamed” claytoniana (Clinton not involved!) is kind of promiscuitive fern, longing for reproduction with any and every fern?? So why not, it’s all in the sense of evolution, no more or less.
Back into seriosity: I don’t believe there are truly hybrids between Cinnamon and Interrupted fern, so we need reliable evidence for.

Donlubin wrote: that’s why we sent it to Japan

Erwin asked:
Do you know about reliable evidence for existing hybrid Osmundastrum cinnamomeum × [Clayt]Osmunda claytonia @dalea @donlubin @milopyne @crothfels @choess @jsmetzgar @mwtreftig ?

The last two comments to this observation have already been added, see above, at answer to the other observation, thus no need for repetition here.

End of part 3 of the whole conversation, the discussion may well be proceeded here.