Recognition of xOsmunasium nothgen. nov. [PASSED]

[choess]

Name of taxon

xOsmunasium

Rank of taxon

Nothogenus

Approximate number of species affected

1

Description of change

This proposal recognizes the nothogenus x Osmunasium for hybrids between the genera Osmunda and Plenasium (Osmundaceae). It contains one species: x Osmunasium x mildei, a hybrid between Osmunda japonica and Plenasium vachellii.

Reason for change

Nothotaxa are planned to be recognized in PPG II. If Claytosmunda and Plenasium are separated from Osmunda s.s. as genera, as in PPG I, this species becomes an intergeneric hybrid.

Spore viability of the hybrid is low, and it is of very uncommon occurrence in Asia. (Tsutsumi et al. 2012)

The first valid name for this nothogenus is x Osmunasium Hong M.Liu, Schuettp. & H.Schneid. (Liu et al. 2020)

Alternatively, PPG II could revert to recognizing a broadly circumscribed but monophyletic Osmunda which would render this nothogenus superfluous. However, Claytosmunda and Plenasium are believed to have diverged from Osmunda s.s. in the Jurassic and Cretaceous, respectively, and they can be identified and distinguished in the fossil record. (Bomfleur et al. 2017).

Bomfleur B, Grimm GW, McLoughlin S. 2017. The fossil Osmundales (royal ferns)—a phylogenetic network analyses, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes. PeerJ 5: 3433. https://doi.org/10.7717/peerj.3433

Hong-Mei Liu, Eric Schuettpelz, Harald Schneider. 2020. Evaluating the status of fern and lycophyte nothotaxa in the context of the Pteridophyte Phylogeny Group classification (PPG I). Journal of Systematics and Evolution 58(6): 988-1002. https://doi.org/10.1111/jse.12641

C. Tsutsumi, Y. Hirayama, M. Kato, Y. Yatabe-Kakugawa, S-Z. Zhang. 2012. Molecular Evidence on the Origin of Osmunda ×mildei (Osmundaceae). American Fern Journal 102(1):55-68.https://doi.org/10.1640/0002-8444-102.1.55

Reference(s) for publication of the name

Hong-Mei Liu, Eric Schuettpelz, Harald Schneider. 2020. Evaluating the status of fern and lycophyte nothotaxa in the context of the Pteridophyte Phylogeny Group classification (PPG I). Journal of Systematics and Evolution 58(6): 988-1002. https://doi.org/10.1111/jse.12641

List the numbers of any related issues

9

Code of Conduct

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

[schwartsburd]

Looks convincing to me. Although I personally think sometimes there is an over-exageration on the number of recognized genera, in this specific case the genera represent old lineages that diverged apart hundreds of millions of years ago. I am in favor of this proposal.

[joelnitta]

FYI, please see the related discussion about circumscription of Osmunda: https://github.com/pteridogroup/ppg/discussions/24

[joelnitta]

This proposal was voted on during PPG Ballot 1 (voting period July 2023). A total of 46 votes were cast. There were 42 'Yes' votes (91.3%) and 4 'No' votes (8.7%). The proposal passes.

[joelnitta]

Already implemented in data, closing.