Recognition of Hovenkampia segregated from Pyrrosia s.l. (Polypodiaceae) [PASSED]

[gonggashan88]

Author(s) of proposal

Li-Bing Zhang, Xin-Mao Zhou

Name of taxon

Hovenkampia

Rank of taxon

Genus

Approximate number of species affected

3

Description of change

Hovenkampia has been segregated from Pyrrosia. The new genus is in honor of the late Professor Peter Hovenkamp.

Reason for change

Hovenkampia and Pyrrosia s.s. have been resolved as paraphyletic in relation to Platycerium (staghorn or elkhorn ferns) based on plastid data. In other words, Hovenkampia is sister to Platycerium (Wei et al., 2017; Zhou et al., 2017). Unless Platycerium (1827) is synonymized with Pyrrosia (1803), Hovenkampia must be split from Pyrrosia s.l. (Zhou et al., 2017). Nucear LEAFY data resolved Hovenkampia within Pyrrosia s.l. by Wei et al. (2017), suggesting possible ancient ancient hybridization or incomplete lineage sorting, but more nuclear data are needed.

Morphologically, Hovenkampia is similar to Pyrrosia s.s., but the former has completely parenchymatous rhizome, secondary veins hardly distinct from the other veins, polocytic stomata, and relatively small sporangia (Zhou et al., 2017). Hovenkamp (1986) already found that Hovenkampia, Pyrrosia s.s., and Platycerium formed an unresolved trichotomy based morphology only.

Three species in Hovenkampia all occur in Africa only.

Reference(s) for publication of the name

Wei, X, Y Qi, X Zhang, L Luo, H Shang, R Wei, H Liu, B Zhang. 2017. Phylogeny, historical biogeography and characters evolution of the drought resistant fern Pyrrosia Mirbel (Polypodiaceae) inferred from plastid and nuclear markers. Scientific Reports 7: 12757. DOI:10.1038/s41598-017-12839-w.

Zhou X-M, L Zhang, CW Chen, C-X Li, YM Huang, D-K Chen, NT Lu, D Cicuzza, R Knapp, TT Luong, JH Nitta, X-F Gao, L-B Zhang. 2017. A plastid phylogeny and character evolution of the Old World fern genus Pyrrosia (Polypodiaceae) with the description of a new genus: Hovenkampia (Polypodiaceae). Molecular Phylogenetics and Evolution 114: 271–294.

List the numbers of any related issues

No response

Code of Conduct

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

[joelnitta]

Links to papers:

• Wei et al. (2017)
• Zhou et al. (2017)

[crothfels]

The proposals this month are doozies!! This story appears straightforward if you look at the plastid data, but I don't see how to reconcile the nuclear result. Someone correct me if I make a mistake, but it seems to me that the position of Hovenkampia in the nuclear data isn't explainable by ancient hybridization, because the Hovenkampia sequences are very similar to P.laevis etc ones. That wouldn't be possible if the hybridization even happened a long time ago. Similarly, I don't see how ILS can explain these results. Coalescence can only ever happen below (before) a species-divergence, so there's no way to get Platycerium alleles into Hovenkampia given how recently the nuclear alleles diverged from this in P.laevis. The only thing I can imagine is that Hovenkampia is of (recent) allopolyploid origin between an unsampled lineage related to Platycerium and something closely related to P.laevis. But that seems really far-fetched too!! If any of the Wei et al. authors are here, could you explain a bit more how the nuclear data were handled? It looks like they were directly sequenced (no cloning, etc)? In which case there might be homeologous copies that weren't recovered?

[khorikhori]

If Hovenkampia is allopolyploid origin between Platycerium s.s. and Pyrrosia s.s., it should have a similar nuclear sequence of Platycerium but in the LFY there is only that of Pyrrosia s.s. If Hovenkampia has really similar sequence of Platycerium, Platycerium and Pyrrosia need to be merged as the same genus but I don't think so because morphological characters of Hovenkampia are not intermediate between these two genus. It is difficult to define ILS but sometimes ILS can be appeared if short region of DNA sequences are used for phylogenetic analysis. The speed of substitutions are various each genes especially in nuclear genome, recombination ocurred more frequently than plastid genome.

[gonggashan88]

I can be wrong, but I remember there are two copies of LEAFY in at least some groups of ferns, a longer one and shorter one. I guess Wei et al. (2017) used one of the copies for their nuclear phylogeny.

[joelnitta]

This proposal was voted on during PPG Ballot 8 (voting period February 2024). A total of 57 votes were cast. There were 43 'Yes' votes (75.4%) and 14 'No' votes (24.6%). The proposal passes.