Abstract
The taxonomy of Spiranthes is highly challenging due to its phenotypic plasticity, morphological convergence, and hybridization. This paper presents a re-evaluation of the genus Spiranthes (Orchidaceae) in Taiwan, with special reference to the taxonomic identity of S. suishaensis that has often been considered the earlier name of S. nivea or S. hongkongensis. Nonetheless, the floral dissection of the type specimen revealed that S. suishaensis has a well-developed rostellum that separates the stigma and pollinarium of each flower, in contrast to autogamous taxa such as S. nivea and S. hongkongensis. Given the morphological evidence and that only S. sinensis was collected in the S. suishaensis type locality, we concluded that S. suishaensis is neither an earlier name for S. nivea nor S. hongkongensis but a synonym of S. sinensis. During morphological comparisons of S. suishaensis with other taxa of S. sinensis complex, we also found that the taxon illegitimately described as “S. minutiflora” could be treated as a variant of S. nivea. Given that it is distinguishable from S. nivea var. nivea by its more densely pubescent rachis and ovaries (vs. sparsely pubescent rachis and ovaries), narrower sepals with white tinged with pink or purple at apex (vs. wider and entirely white sepals), and papillose labellum disc (vs. almost glabrous labellum disc), we described it as a new variety of S. nivea, which we propose to name S. nivea var. papillata T.C. Hsu & Suetsugu. Consequently, we concluded that three species (S. sinensis, S. hongkongensis, and S. nivea [including var. nivea and var. papillata]) and one hybrid, S. australis × S. sinensis, occur in Taiwan.
References
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Ames, O. (1908) Orchidaceae: Illustrations and studies of the family Orchidaceae. Houghton, Mifflin. 53 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Brown, R. (1810) Prodromus florae novae Hollandae et insulae Van-Diemen. 1st ed. Taylor, London. 592 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Chen, S.-C., Gale, S.W. & Cribb, P.J. (2009) Spiranthes. Flora of China 25: 84–86. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Dueck, L.A., Aygoren, D. & Cameron, K.M. (2014) A molecular framework for understanding the phylogeny of Spiranthes (Orchidaceae), a cosmopolitan genus with a North American center of diversity. American Journal of Botany 101: 1551–1571. https://doi.org/10.3732/ajb.1400225</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hayata, B. (1916) Icones plantarum formosanarum nec non et contributiones ad floram formosanam. Bureau of Productive Industry, Government of Formosa, Taihoku. 86 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hsu, T.C. & Chung, S.W. (2014) Spiranthes hongkongensis (Orchidaceae): Newly recorded from Taiwan. Taiwan Journal of Biodiversity 16: 405–408. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hsu, T.-C. & Chung, S.-W. (2016) The illustrated flora of Taiwan. Owl Publishing House, Taipei. 408 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hu, S.Y. & Barretto, G. (1976) New species and varieties of Orchidaceae from Hong Kong. Chung Chi Journal 13: 1–34. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lang, K.Y. (1999) Spiranthes. In: Lang, K.Y. (ed.) Flora Republicae Popularis Sinicae 17: 228–231. Science Press, Beijing.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P. (1975) Native orchids of Taiwan, vol. 1. Ji-Chyi Wang, Chiayi. 271 pp.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P. (2019) The orchid flora of Taiwan: A collection of line drawings. National Taiwan University Press, Taipei. 1012 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.P. & Lin, W.M. (2011) Newly discovered native orchids of Taiwan (IV). Taiwania 56: 315–322. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P., Liu, H.-Y., Hsieh, C.-F. & Wang, K.-H. (2016) Complete list of the native orchids of Taiwan and their type information. Taiwania 61: 78–126. https://doi.org/10.6165/tai.2016.61.78</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Liu, T.S. & Su, H.J. (1978) Orchidaceae. In: Li, H.L. et al. (eds.) Flora of Taiwan 5. Epoch, Taipei. pp. 859–1137.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lindley, J. (1824) Spiranthes australis. The Botanical Register 10: t. 823. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C. & Cameron, K.M. (2017) The systematics of the Spiranthes cernua species complex (Orchidaceae): Untangling the Gordian Knot. Systematic Botany 42: 1–30. https://doi.org/10.1600/036364417X696528 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C. & Cameron, K.M. (2020) The enduring value of specimen-based research: a response to Surveswaran et al. (2020). Botanical Journal of the Linnean Society 194: 382–384. https://doi.org/10.1093/botlinnean/boaa069</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C., Giraldo, G., Frericks, J., Lehnebach, C.A. & Cameron, K.M. (2019) Illuminating the systematics of the Spiranthes sinensis species complex (Orchidaceae): ecological speciation with little morphological differentiation. Botanical Journal of the Linnean Society 189: 36–62. https://doi.org/10.1093/botlinnean/boy072</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Persoon, C.H. (1807) Synopsis plantarum, seu Enchiridium botanicum, complectens enumerationem systematicam specierum hucusque cognitarum. Vol. 2. pp. 511. https://doi.org/10.5962/bhl.title.638 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Richard, L.-C. (1817) De orchideis europaeis annotationes, praesertim ad genera dilucidanda spectantes. Ex typ. A. Belin, Parisiis. 232 pp. https://doi.org/10.5962/bhl.title.15465</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Richard, A. & Galeotti, H.G. (1845) Orchidographie Mexicaine, d’après les échantillons, notes et dessins de MM. Galeotti, Linden, Funck, Ghiesbreght. Annales des Sciences Naturelles, Botanique, sér. 3 3: 15–33.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Schlechter, R. (1919) Repertorium specierum novarum regni vegetabilis. Selbstverlag des Herausgebers, Berlin.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Suetsugu, K. & Hayakawa, H. (2019) Spiranthes hongkongensis SY Hu & Barretto (Orchidaceae): Newly discovered orchid on Ishigaki Island, Ryukyu Islands, Japan. Acta Phytotaxonomica et Geobotanica 70: 205–208. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Suetsugu, K., Lin, J.-Z., Hsu, T.-C. & Hayakawa, H. (2020) Interspecific hybridization between Spiranthes australis and S. sinensis (Orchidaceae) in southern Taiwan. Acta Phytotaxonomica et Geobotanica 71: 177–184. https://doi.org/10.18942/apg.201922 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Gowda, V. & Sun, M. (2018) Using an integrated approach to identify cryptic species, divergence patterns and hybrid species in Asian ladies’ tresses orchids (Spiranthes, Orchidaceae). Molecular Phylogenetics and Evolution 124: 106–121. https://doi.org/10.1016/j.ympev.2018.02.025 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Gowda, V. & Sun, M. (2020) Cryptic species and taxonomic troubles: a rebuttal of the systematic treatment of the Asian ladies’ tresses orchids (Spiranthes species; Orchidaceae) by Pace et al. (2019). Botanical Journal of the Linnean Society 194: 375–381. https://doi.org/10.1093/botlinnean/boaa068</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Kumar, P. & Sun, M. (2017) Spiranthes himalayensis (Orchidaceae, Orchidoideae) a new species from Asia. PhytoKeys 89: 115–128. https://doi.org/10.3897/phytokeys.89.19978</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Tao, Z.-B., Ren, Z.-X., Bernhardt, P., Liang, H., Li, H.-D., Zhao, Y.-H., Wang, H. & Li, D.-Z. (2018) Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas? Ecology and Evolution 8: 5455–5469. https://doi.org/10.1002/ece3.4067 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Ying, S.-S. (2022) New Taxa & New Names, Volume Three. Shao-Shun Ying, Taipei, Taiwan. 304 pp.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Brown, R. (1810) Prodromus florae novae Hollandae et insulae Van-Diemen. 1st ed. Taylor, London. 592 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Chen, S.-C., Gale, S.W. & Cribb, P.J. (2009) Spiranthes. Flora of China 25: 84–86. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Dueck, L.A., Aygoren, D. & Cameron, K.M. (2014) A molecular framework for understanding the phylogeny of Spiranthes (Orchidaceae), a cosmopolitan genus with a North American center of diversity. American Journal of Botany 101: 1551–1571. https://doi.org/10.3732/ajb.1400225</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hayata, B. (1916) Icones plantarum formosanarum nec non et contributiones ad floram formosanam. Bureau of Productive Industry, Government of Formosa, Taihoku. 86 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hsu, T.C. & Chung, S.W. (2014) Spiranthes hongkongensis (Orchidaceae): Newly recorded from Taiwan. Taiwan Journal of Biodiversity 16: 405–408. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hsu, T.-C. & Chung, S.-W. (2016) The illustrated flora of Taiwan. Owl Publishing House, Taipei. 408 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Hu, S.Y. & Barretto, G. (1976) New species and varieties of Orchidaceae from Hong Kong. Chung Chi Journal 13: 1–34. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lang, K.Y. (1999) Spiranthes. In: Lang, K.Y. (ed.) Flora Republicae Popularis Sinicae 17: 228–231. Science Press, Beijing.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P. (1975) Native orchids of Taiwan, vol. 1. Ji-Chyi Wang, Chiayi. 271 pp.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P. (2019) The orchid flora of Taiwan: A collection of line drawings. National Taiwan University Press, Taipei. 1012 pp. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.P. & Lin, W.M. (2011) Newly discovered native orchids of Taiwan (IV). Taiwania 56: 315–322. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lin, T.-P., Liu, H.-Y., Hsieh, C.-F. & Wang, K.-H. (2016) Complete list of the native orchids of Taiwan and their type information. Taiwania 61: 78–126. https://doi.org/10.6165/tai.2016.61.78</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Liu, T.S. & Su, H.J. (1978) Orchidaceae. In: Li, H.L. et al. (eds.) Flora of Taiwan 5. Epoch, Taipei. pp. 859–1137.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lindley, J. (1824) Spiranthes australis. The Botanical Register 10: t. 823. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C. & Cameron, K.M. (2017) The systematics of the Spiranthes cernua species complex (Orchidaceae): Untangling the Gordian Knot. Systematic Botany 42: 1–30. https://doi.org/10.1600/036364417X696528 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C. & Cameron, K.M. (2020) The enduring value of specimen-based research: a response to Surveswaran et al. (2020). Botanical Journal of the Linnean Society 194: 382–384. https://doi.org/10.1093/botlinnean/boaa069</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pace, M.C., Giraldo, G., Frericks, J., Lehnebach, C.A. & Cameron, K.M. (2019) Illuminating the systematics of the Spiranthes sinensis species complex (Orchidaceae): ecological speciation with little morphological differentiation. Botanical Journal of the Linnean Society 189: 36–62. https://doi.org/10.1093/botlinnean/boy072</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Persoon, C.H. (1807) Synopsis plantarum, seu Enchiridium botanicum, complectens enumerationem systematicam specierum hucusque cognitarum. Vol. 2. pp. 511. https://doi.org/10.5962/bhl.title.638 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Richard, L.-C. (1817) De orchideis europaeis annotationes, praesertim ad genera dilucidanda spectantes. Ex typ. A. Belin, Parisiis. 232 pp. https://doi.org/10.5962/bhl.title.15465</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Richard, A. & Galeotti, H.G. (1845) Orchidographie Mexicaine, d’après les échantillons, notes et dessins de MM. Galeotti, Linden, Funck, Ghiesbreght. Annales des Sciences Naturelles, Botanique, sér. 3 3: 15–33.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Schlechter, R. (1919) Repertorium specierum novarum regni vegetabilis. Selbstverlag des Herausgebers, Berlin.</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Suetsugu, K. & Hayakawa, H. (2019) Spiranthes hongkongensis SY Hu & Barretto (Orchidaceae): Newly discovered orchid on Ishigaki Island, Ryukyu Islands, Japan. Acta Phytotaxonomica et Geobotanica 70: 205–208. </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Suetsugu, K., Lin, J.-Z., Hsu, T.-C. & Hayakawa, H. (2020) Interspecific hybridization between Spiranthes australis and S. sinensis (Orchidaceae) in southern Taiwan. Acta Phytotaxonomica et Geobotanica 71: 177–184. https://doi.org/10.18942/apg.201922 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Gowda, V. & Sun, M. (2018) Using an integrated approach to identify cryptic species, divergence patterns and hybrid species in Asian ladies’ tresses orchids (Spiranthes, Orchidaceae). Molecular Phylogenetics and Evolution 124: 106–121. https://doi.org/10.1016/j.ympev.2018.02.025 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Gowda, V. & Sun, M. (2020) Cryptic species and taxonomic troubles: a rebuttal of the systematic treatment of the Asian ladies’ tresses orchids (Spiranthes species; Orchidaceae) by Pace et al. (2019). Botanical Journal of the Linnean Society 194: 375–381. https://doi.org/10.1093/botlinnean/boaa068</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Surveswaran, S., Kumar, P. & Sun, M. (2017) Spiranthes himalayensis (Orchidaceae, Orchidoideae) a new species from Asia. PhytoKeys 89: 115–128. https://doi.org/10.3897/phytokeys.89.19978</span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Tao, Z.-B., Ren, Z.-X., Bernhardt, P., Liang, H., Li, H.-D., Zhao, Y.-H., Wang, H. & Li, D.-Z. (2018) Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas? Ecology and Evolution 8: 5455–5469. https://doi.org/10.1002/ece3.4067 </span></span></span>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Ying, S.-S. (2022) New Taxa & New Names, Volume Three. Shao-Shun Ying, Taipei, Taiwan. 304 pp.</span></span></span>