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| Spiranthes minamitaniana Suetsugu, in Suetsugu, Hirota et Suyama, 2023. オスズネジバナ || DOI: 10.11646/phytotaxa.599.3.1 |
Abstract
The delimitation of species within the genus Spiranthes (Orchidaceae) is problematic due to the intricate interplay of phenotypic plasticity, ecological variation, and hybridization, making identification that relies solely on morphology inadequate. In light of morphological and phylogenetic data, we have described a self-pollinating species, Spiranthes minamitaniana within the Spiranthes sinensis species complex. Spiranthes minamitaniana shares several morphological features with S. hachijoensis, such as glabrous inflorescence rachis, ovaries, and sepals, a degenerated rostellum, pollinia without a viscidium, and papillate lip basal callosities. However, it can be distinguished by several morphological traits, including semicircular, weakly- or non-3-lobed stigma, and more conspicuous anther cap. Although S. minamitaniana is morphologically most similar to S. hachijoensis, phylogenetic analysis strongly suggested that S. minamitaniana has independently acquired a selfing reproductive mode and constitutes a separate genetic cluster from it. As such, this taxon is morphologically and phylogenetically distinct from other closely related species. Consequently, this taxon is morphologically and phylogenetically distinct from other closely related species.
Key words: Orchidaceae, integrative taxonomy, reproductive isolation, SNP data, species delimitation, Spiranthes sinensis species complex
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| Spiranthes minamitaniana in its type locality. (A) Habit. (B) Inflorescence with whitish cleistogamous flower. (C–D) Flower. Scale bars: 30 mm (A) and 5 mm (B–D). |
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| Spiranthes minamitaniana with reddish pink normal flower (Tadashi Minamitani Ss146, KYO). (A) Inflorescence. (B) Flower, lateral view. (C) Flower, dorsal view. (D) Dorsal sepal. (E) Petal. (F) Lateral sepal. (G) Labellum. (H) Close-up of basal callosities of labellum. (I) Ovary and column. (J) Column, ventral view. (K) Column, dorsal view. (L) Pollinarium. Scale bars: 20 mm (A), 3 mm (B–G), 0.5 mm (H) and 1 mm (I–M). |
Spiranthes minamitaniana Suetsugu, sp. nov.
Japanese name. 「オスズネジバナ」 Osuzu-neji-bana
Diagnosis. Spiranthes minamitaniana is morphologically most similar to S. hachijoensis but differs from S. hachijoensis by semicircular, weakly- or non-3-lobed stigma, and more conspicuous anther cap.
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| Comparison between Spiranthes hachijoensis (Nahoko Fukudome Ss203, KYO: left) and Spiranthes minamitaniana (Tadashi Minamitani Ss204, KYO: right). (A) Habit. (B) Inflorescence. (C) Flower. (D) Column, dorsal view. (E) Column, lateral view. (F) Column, ventral view. Scale bars: 50 mm (A), 10 mm (B), 3 mm (C) and 1 mm (D–F). Photographed by Kenji Suetsugu |
Kenji Suetsugu, Shun K. Hirota and Yoshihisa Suyama. 2023. Spiranthes minamitaniana (Orchidaceae), A New Orchid Species from Japan based on Morphological and Phylogenetic Data. Phytotaxa. 599(3); 139-149. DOI: 10.11646/phytotaxa.599.3.1
