schwartsburd
commented
1 year ago In favor. Lindsaea and Odontosoria are two very distinct genera that are better to be kept as separated. The hybrid is well documented, and leaves zero or little doubt about its identity. In favor of recognizing xLindsaeosoria
joelnitta
Author(s) of proposal
Samuli Lehtonen
Name of taxon
×Lindsaeosoria
Rank of taxon
Nothogenus
Approximate number of species affected
1
Description of change
Recognition of the nothogenus ×Lindsaeosoria W.H.Wagner, a taxon of hybrid origin between Lindsaea Dryand. ex Sm. and Odontosoria Fée.
Reason for change
Nothogenera were not recognized in PPG I, but will be in PPG II. For this reason, I propose the recognition of nothogenus ×Lindsaeosoria with a single nothospecies ×Lindsaeosoria flynnii W.H.Wagner.
×Lindsaeosoria is a hybrid genera between Lindsaea and Odontosoria (Lindsaeaceae). The morphologically distinct parental genera have traditionally been accepted, also in PPG I, and are generally not resolved as sister taxa (e.g. Lehtonen et al. 2010). It has been estimated that their divergence from a common ancestor dates back to Late Cretaceous or Early Paleogene (Regalado et al. 2017, Testo and Sundue 2016). The hybrid, ×Lindsaeosoria flynnii, was found in Hawaii growing mixed with its presumed parental species, Odontosoria chinensis (L.) J. Sm. and Lindsaea ensifolia Sw. (Wagner 1993). The hybrid origin of ×Lindsaeosoria flynnii was already well-established by its unique morphology combining characters of its presumed parental taxa and abortive spores (Wagner 1993). Molecular study revealed a close affinity of the hybrid with L. ensifolia in plastid phylogeny, while targeted Illumina sequencing of the second intron of the nuclear LEAFY gene revealed presence of distinct alleles, which grouped with the presumed parental species in phylogenetically distinct positions (Lehtonen 2018). Accepting the well-established parental genera and ×Lindsaeosoria as a a hybrid nothogenus between them appears to be the most reasonable solution for the taxonomy of these taxa, as already suggested by Liu et al. (2020), and is proposed here.
An alternative solution, lumping the parental genera, would create a large and morphologically ill-founded genus, that would justify lumping all the other, morphologically less distinct genera of the family as well. Indeed, given their phylogenetic relationships, this might be the only way to preserve the monophyly of such a genus. Hence, I consider this option taxonomically highly disruptive and unacceptable.
Reference(s) for publication of the name
Liu, H.M., Schuettpelz, E., & Schneider, H. 2020. Evaluating the status of fern and lycophyte nothotaxa in the context of the Pteridophyte Phylogeny Group classification (PPG I). J. Syst. Evol. 58: 988–1002. https://doi.org/10.1111/jse.12641
Lehtonen, S. 2018. ×Lindsaeosoria flynnii (Lindsaeaceae), another confirmed example of deep hybridization among the ferns. Am. Fern J. 108: 7–18. https://doi.org/10.1640/0002-8444-108.1.7
Lehtonen, S., Tuomisto, H., Rouhan, G., Christenhusz, M.J.M. 2010. Phylogenetics and classification of the pantropical fern family Lindsaeaceae. Bot. J. Linn. Soc. 163: 305–359. https://doi.org/10.1111/j.1095-8339.2010.01063.x
Regalado, L., Schmidt, A.R., Appelhans, M.S., Ilsemann, B., Schneider, H., Krings, M. Heinrichs, J. 2017. A fossil species of the enigmatic early polypod fern genus Cystodium (Cystodiaceae) in Cretaceous amber from Myanmar. Sci. Rep. 7: 14615. https://doi.org/10.1038/s41598-017-14985-7
Testo, W., Sundue, M. 2016. A 4000-species dataset provides new insight into the evolution of ferns. Mol. Phylogenet. Evol. 105: 200–211. https://doi.org/10.1016/j.ympev.2016.09.003
Wagner, W.H. 1993. New species of Hawaiian pteridophytes. Contr. Univ. Michigan Herb. 19: 63–82.
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