Resurrection of Huperziaceae (Lycopodiales) [NOT PASSED]

[gonggashan88]

Author(s) of proposal

Li-Bing Zhang, Xin-Mao Zhou

Name of taxon

Huperziaceae

Rank of taxon

Family

Approximate number of species affected

280

Description of change

Recognition of two families in Lycopodiales: Huperziaceae and Lycopodiaceae s.s. This resurrection won't change any names of species or genera.

Reason for change

We advocate for the recognition of Huperziaceae for three reasons: morphological diagnosability, spore ornamentation, and deep divergence between Huperziaceae and Lycopodiaceae s.s.

(1) There are a number of morphological characters defining Huperziaceae (Zhang & Iwatsuki, 2013; Øllgaard & Windisch, 2016; Chen et al., 2022; Zhang & Zhou, 2022). Notably, the spore ornamentations in Huperziaceae are exclusively foveolate-fossulate, whereas those in Lycopodiaceae are reticulate, scabrate, baculate, rugulate, or nearly reticulate (Chen et al., 2022; Zhang & Zhou, 2022).

(2) Ancient divergence: Testo et al. (2018) estimated a divergence time between Huperziaceae and Lycopodiaceae s.s. as 368.4 million years ago (mya) vs. 377.8 mya between Isoëtales and Selaginellales; or as 308.8 mya vs. 362.7 mya based on the uncorrelated lognormal clock model.

(3) Recognizing Huperziaceae is not new and a number of botanists favored two families in Lycopodiales [Rothmaler, 1944, 1962 (as Urostachyaceae); Ching, 1978, 1983; Holub, 1985; Zhang & Kung, 2000; Haines, 2003; Zhang, 2004].

Huperziaceae contain three genera: Huperzia with ca. 30 spp., Phlegmariurus with ca. 250 spp., and Phylloglossum with 1 sp.

Reference(s) for publication of the name

Haines, 2003_ The families Huperziaceae and Lycopodiaceae in New England Zhang & Iwatsuki, 2013, Flora of China. Ollgaard & Windish 2016_Brazil Lycopodiaceae.pdf Testo et al. 2018_Lycopodiaceae biogeography.pdf Chen et al 2022_Lycopodiaceae.pdf Zhang & Zhou 2022_classification of Lycopodiales.pdf

List the numbers of any related issues

No response

Code of Conduct

• [X] I agree to follow the PPG Code of Conduct

[wtesto]

Hi Li-Bing,

Thanks for this proposal - I'll take this opportunity to weigh in. While this is certainly a monophyletic group, I am not in favor of recognizing it as a family, mostly because I think that Lycopodiaceae in the sense used by most authors (and by PPG 1) is much more readily diagnosable morphologically. I think that this is the reason that most students of the group, have not recognized Huperziaceae. This includes all of the publications you cite as references, except for Arthur Haines' treatment for New England, USA.

Lycopodiaceae in the commonly used circumscription can be easily recognized - they are homosporous plants with eligulate microphylls, trilete spores, and protosteles. Based on my understanding of the morphology of the plants and the results of the papers that you cite, Huperziaceae is characterized morphologically principally by spore ornamentation. The inclusion of Phylloglossum in this clade makes Huperziaceae rather morphologically heterogeneous and difficult to characterize, n my opinion.

I also worry that applying the criterion of divergence times here is fraught - drawing from the Testo et al. 2018 paper that is cited here, all or nearly all genera of Lycopodiaceae (sensu PPG 1) diverged prior to the K-T boundary. Given that these genera are often roughly as old as many fern families and are probably more readily morphologically diagnosable than Huperziaceae/Lycopodiaceae s.s., one could just as readily push to recognize these all as families.

Finally, I don't know if the fact that a name has already been published is a compelling reason for us to take it back up here. While there are several publication that have adopted the use of Huperziaceae since it was first published by Rothmaler, these are a rather small minority. Most taxonomists working these plants have chosen to recognize this clade at the subfamily level.

For the same reasons of morphological diagnosability and concerns about using clade age as a criterion for rank assignment, I prefer to not recognize Lycopodiastroideae. I would also be opposed to the recognition of Lycopodielloideae, though I would find that would be an easier clade to diagnose on the basis of morphology than Huperziaceae would be.

Best, Wes

[DrAshleyField]

Hi Li-Bing,

I agree with Wes, my preference is for a single-family Lycopodiaceae, keeping Huperzioideae as a subfamily. In addition to the reasons proposed above, two reasons for my preference relate to teaching field and herbarium botany:

(1) Lycopodiaceae is readily diagnosable in the field based on numerous macro-morphological features and hand lens features. Huperzioideae is diagnosable on one or perhaps two microscopic features. There are macro-morphological features that ALMOST work (tufted branches, tufted epicorticular roots, isodichotomy) but there are so many exceptions in Phlegmariurus and the exceptional Phylloglossum.

(2) Lycopodiaceae has a long and stable popular science history as an educational tool. It is often the only thing a user knows about these plants, and they can use that key to access more knowledge.

Where a Family is already monophyletic, diagnosable, stable, popular and still useful in its current form, I prefer retaining those benefits.

Regards, Ashley

[EdgarJRincon]

Estoy de acuerdo con Wes y Ashley Lycopodiacea como unica familia funciona muy bien.

Buenas tardes

Edgar

[gonggashan88]

Hi Wes, Ashley and Edgar, thanks for your comments. In the six references I cited, In addition to Arthur Haines' treatment, Zhang & Zhou (2022) also adopted Huperziaceae. I am sure you know a lot of references in which Huperziaceae (= Urostachyaceae) is constantly adopted, e.g., Rothmaler (1944), Ching (1978, 1981a, b, 1982), Zhang & Kung (1998, 1999, 2000, Zhang (2004; Flora of China), Ji et al. (2008), Hsieh (2012), Xu et al. (2017), Weakley (2020), Weakley & Southeastern Flora Team (2022, 2023, 2024), quite a few US state floras, ... and quite a few online sites including Michael Sundue's Ferns of the World: https://www.fernsoftheworld.com/fow_family/huperziaceae/

Yes, the broadly defined Lycopodiaceae is dominant because (1) Lycopodiaceae is an older name and plants of Lycopodiaceae s.s. are more common; and (2) the literature in the past 40+ years has been influenced mainly by our dear colleague, Prof. B. Øllgaard, who adopted Lycopodiaceae s.l. We know Polypodiaceae s.l. had been dominant too, but we now recognize 20+ families segregated from Polypodiaceae s.l.

No, spore ornamentation is not the only feature defining the two families. What distinguishes the two current subfamilies, Huperzioideae and Lycopodioideae, distinguishes the two families too. For example, horizontal stems absent, shoots clustered, roots usually in single basal clump in H. vs. horizontal stems present, shoots non-clustered, roots emerging at intervals along horizontal stem in L.

Well, I see your point about divergence times. On the other hand, divergence time is not the only criterium we use when deciding a taxonomic rank, right?

Similar arguments can be applied to the recognition of Lycopodiastroideae: morphology, phylogeny, and ancient divergence.

Best wishes, Li-Bing

[msundue]

Great discussion everyone.

Since my name and ferns of the world was mentioned, I should point out that the content of FOTW posts belong to the authors of that post, not me. They reflect the taxonomic choice of the authors at that time and should not be considered a formal classification or one that I promote or impose. I do spend a lot of time developing the site, but the content really belongs to the contributors.

By the way, if anyone wants to submit posts, please get in touch! Direct message me at @.*** and I will get you started.

Best, Michael

On Tue, Apr 2, 2024 at 8:27 PM Li-Bing Zhang @.***> wrote:

Hi Wes, Ashley and Edgar, thanks for your comments. In the six references I cited, In addition to Arthur Haines' treatment, Zhang & Zhou (2022) also adopted Huperziaceae. I am sure you know a lot of references in which Huperziaceae (= Urostachyaceae) is constantly adopted, e.g., Rothmaler (1944), Ching (1978, 1981a, b, 1982), Zhang & Kung (1998, 1999, 2000, Zhang (2004; Flora of China), Ji et al. (2008), Hsieh (2012), Xu et al. (2017), Weakley (2020), Weakley & Southeastern Flora Team (2022, 2023, 2024), quite a few US state floras, ... and quite a few online sites including Michael Sundue's Ferns of the World: https://www.fernsoftheworld.com/fow_family/huperziaceae/

Yes, the broadly defined Lycopodiaceae is dominant because (1) Lycopodiaceae is an older name and plants of Lycopodiaceae s.s. are more common; and (2) the literature in the past 40+ years has been influenced mainly by our dear colleague, Prof. B. Øllgaard, who adopted Lycopodiaceae s.l. We know Polypodiaceae s.l. had been dominant too, but we now recognize 20+ families segregated from Polypodiaceae s.l.

No, spore ornamentation is not the only feature defining the two families. What distinguishes the two current subfamilies, Huperzioideae and Lycopodioideae, distinguishes the two families too. For example, horizontal stems absent, shoots clustered, roots usually in single basal clump in H. vs. horizontal stems present, shoots non-clustered, roots emerging at intervals along horizontal stem in L.

Well, I see your point about divergence times. On the other hand, divergence time is not the only criterium we use when deciding a taxonomic rank, right?

Similar arguments can be applied to the recognition of Lycopodiastroideae: morphology, phylogeny, and ancient divergence.

Best wishes, Li-Bing

— Reply to this email directly, view it on GitHub https://github.com/pteridogroup/ppg/issues/75#issuecomment-2032943480, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABXVFQXUPLFIIAHOTGGUGFTY3MBDPAVCNFSM6AAAAABDHXVJKKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDAMZSHE2DGNBYGA . You are receiving this because you are subscribed to this thread.Message ID: @.***>

-- Michael Sundue Fernsoftheworld.com

[DrAshleyField]

Hi Libing, Wes, Edgar, Michael,

Some exceptions to the character break down are:

Horizontal/lateral subterranean stems (+/- leafless) with non-tufted roots emerging along them are common in epiphytic Phlegmariurus carinatus, P. creber, P. dalhousieanus, P. hippuris, P. macgregorii, P. nummulariifolius and others. It is a method that epiphytes specialising in growing in arboreal peat and moss masses spread to form new sites.

Horizontal/lateral (+/- heteroblastic) stems with non-tufted roots emerging along them are also present in numerous terrestrial Neotropical Phlegmariurus such as P. badinianus, the species rich P. crassus group and the Palaeotropical P. saururus and others. By this means the colony spreads over a broader local area, with each vertical stem fed by its own roots that emerge where the horizontal shoot becomes vertical.

One example where the Huperzioid and Lycopodioid macro-morphological characters get murky are the sympatric New Guinean epiphytes P. macgregorii and Lycopodium hygrophyllum, both of which can have anisotomous lateral shoots with non tufted roots and clamber over the surface distributing pendant branches that can be strobilate!

And there remains the exceptional unbranched and strobilate Phylloglossum.

Regards, Ashley

[gonggashan88]

Hi Michael, thanks for clarification :-).

Hi Ashley, I would not worry too much about some exceptions, as long as it works in most cases. We have to live with morphological homoplasy.

You may also agree that the distinction between Huperziaceae and Lycopodiaceae s.s., at least in spore ornamentation, is clearer than that among some families in eupolypods II we recognized. It reminds me of the excellent paper by Riibe et al. (2021) who transferred Diplazium praestans (Athyriaceae) to Hymenasplenium (Aspleniaceae).

No matter how morphologically similar between H. and L., their divergence is nearly as old as that between homo sapiens and the lobe-finned fish.

Best wishes, Libing

Li-Bing Zhang Curator Missouri Botanical Garden

[joelnitta]

This proposal was voted on during PPG Ballot 10 (voting period April 2024). A total of 81 votes were cast. There were 20 'Yes' votes (24.7%) and 61 'No' votes (75.3%). The proposal does not pass.