Recognition of Sahashia (Ophioglossaceae) [PASSED]

[choess]

Name of taxon

Sahashia

Rank of taxon

Genus

Approximate number of species affected

1

Description of change

Recognize Sahashia Li Bing Zhang & Liang Zhang as a segregate genus from Botrypus Michx. sensu PPG I.

Reason for change

The PPG I circumscription of Botrypus Michx. was recognized as non-monophyletic based on Hauk et al. 2003 and Shinohara et al. 2013, which showed the two species placed there (B. strictus (Underw.) Holub and B. virginianus (L.) Michx.) forming a grade at the base of Botrychoideae, with B. strictus sister to the rest of the subfamily.

Zhang et al. 2020 described the new genus Sahashia to accommodate the former B. strictus and make Botrypus (now containing one cryptically diverse species) monophyletic.

Botrypus sensu PPG I could be distinguished from the other genera of Botrychioideae by the site of the junction between sporophore and trophophore (at the base of the sporophore lamina, sharing a common stipe in Botrypus s.l. vs at or near ground level for Sceptridium and above the base of the lamina in Japanobotrych(i)um) and the degree of division of the trophophore (generally tri- to tetrapinnate in Botrypus s.l. vs. not more than bipinnate in Botrychium s.s.). Zhang et al. suggest further distinguishing Sahashia from Botrypus s.s. by its narrow, linear sporophore (vs. deltate in the latter); other characters are given in couplet 6 of the Flora of China Botrychium treatment.

This proposal resolves the lack of monophyly noted in PPG I, which is desirable. The five clades here proposed as genera are readily distinguishable from one another on the basis of gross morphology and certainly deserve formal rank. Rank at genus level is most consistent with the treatment established in PPG I. The principal alternative would be to treat all five genera in Botrychioideae as a broadly circumscribed Botrychium, for which there is historical precedent. Were this course followed, a new combination ought to be made for Sahashia as a subgenus of Botrychium s.l.

Hauk WD, Parks CR, Chase MW. 2003. Phylogenetic studies of Ophioglossaceae: Evidence from rbcL and trnL-F plastid DNA sequences and morphology. Molecular Phylogenetics and Evolution 28: 131–151. https://doi.org/10.1016/S1055-7903(03)00032-0

Shinohara W, Nakato N, Yatabe-Kakugawa Y, Oka T, Kim JK, Murakami N, Noda H, Sahashi N. 2013. The use of matK in Ophioglossaceae phylogeny and the determination of Mankyua chromosome number shed light on chromosome number evolution in Ophioglossaceae. Systematic Botany 38: 564–570. https://doi.org/10.1600/036364413X670232

Liang Zhang, Xue-Ping Fan, Sahanat Petchsri, Lin Zhou, Rossarin Pollawatn, Xin Zhang, Xin-Mao Zhou, Ngan Thi Lu, Ralf Knapp, Sahut Chantanaorrapint, Ponpipat Limpanasittichai, Hang Sun, Xin-Fen Gao, Li-Bing Zhang. 2020. Evolutionary relationships of the ancient fern lineage the adder's tongues (Ophioglossaceae) with description of Sahashia gen. nov. Cladistics 36(4): 380–393. https://doi.org/10.1111/cla.12408

Reference(s) for publication of the name

Liang Zhang, Xue-Ping Fan, Sahanat Petchsri, Lin Zhou, Rossarin Pollawatn, Xin Zhang, Xin-Mao Zhou, Ngan Thi Lu, Ralf Knapp, Sahut Chantanaorrapint, Ponpipat Limpanasittichai, Hang Sun, Xin-Fen Gao, Li-Bing Zhang. 2020. Evolutionary relationships of the ancient fern lineage the adder's tongues (Ophioglossaceae) with description of Sahashia gen. nov. Cladistics 36(4): 380-393. https://doi.org/10.1111/cla.12408

List the numbers of any related issues

No response

Code of Conduct

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

[Ben999999]

It makes sense to recognise Sahashia as a new genus according to morphological and molecular data / analyses presented in Zhang et al. 2020.

[WDHauk23]

I support this proposal. I think it makes no sense to have such a diverse array of morphological variation contained in a single genus. Recognizing Sahashia resolves the non-monophyletic status of Botrypus, which has been supported by several independent investigations.

[joelnitta]

This proposal was voted on during PPG Ballot 2 (voting period August 2023). A total of 65 votes were cast. There were 58 'Yes' votes (89.2%) and 7 'No' votes (10.8%). The proposal passes.

[joelnitta]

Already implemented in data, closing.