• Korean Journal of Plant Taxonomy
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• v.39 no.2
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• pp.63-73
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• 2009

$Iso{\ddot{e}}tes$ L. ($Iso{\ddot{e}}taceae$) is difficult to identify among the infrageneric taxa because of morphological simplicity. Since two species (I. japonica and I. coreana) had been reported, I. jejuensis and I. hallasanensis were described as two new species from Jeju Island, South Korea. The habitats of all species were confirmed by current studies except for I. japonica. We compared the morphological and anatomical characters of seven species, three domestic species and four species in adjacent regions (I. taiwanensis, I. sinensis, I. japonica, and I. asiatica). I. asiatica differs from other species in the lobe number of corm, spreading sporophylls, lack of stomata and degree of velum development. All of the seven species were identified by the characteristics of their mega- and microspores. Especially, it was possible to identify the four species in South Korea by the types of ornamentation on their megaspores. Each species has a specific type of megaspore ornamentation: I. coreana - cristate, I. jejuensis - rugulate, I. hallasanensis - echinate, and I. japonica - reticulate. We also discussed the phylogeny of the genus in East Asia in relation to recent studies based on the second intron of LEAFY sequence and amplified fragment length polymorphism (AFLP) analysis. We suggest strategies for the conservation of the endangered $Iso{\ddot{e}}tes$ species in South Korea.

• Korean Journal of Plant Taxonomy
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• v.48 no.4
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• pp.249-259
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• 2018

$Iso{\ddot{e}}tes$ L. ($Iso{\ddot{e}}taceae$) is a cosmopolitan genus of heterosporous lycopods containing ca. 200 species being found in lakes, streams, and wetlands of terrestrial habitats. Despite its ancient origin, worldwide distribution, and adaptation to diverse environment, species in $Iso{\ddot{e}}tes$ show remarkable morphological simplicity and convergence. Allopolyploidy appears to be a significant speciation process in the genus. These characteristics have made it difficult to assess the phylogenetic relationships and biogeographic history of $Iso{\ddot{e}}tes$ species. In recent years, these difficulties have somewhat been reduced by employing multiple molecular markers. Here, we reconstruct the phylogenetic relationships in East Asian $Iso{\ddot{e}}tes$ species. We also provide their divergence time and biogeographic origin using a fossil calibrated chronogram. East Asian $Iso{\ddot{e}}tes$ species are divided into two clades: I. asiatica and the remaining species. $Iso{\ddot{e}}tes$ asiatica from Hokkaido forms a clade with northeastern Russian and western North American $Iso{\ddot{e}}tes$ species. In clade I, western North America is the source area for the dispersal of $Iso{\ddot{e}}tes$ to Hokkaido and northeastern Russia via the Bering land bridge during the late Miocene. The remaining $Iso{\ddot{e}}tes$ species (I. sinensis, I. yunguiensis, I. hypsophila, I. orientalis, I. japonica, I. coreana, I. taiwanensis, I. jejuensis, I. hallasanensis) from East Asia form a sister group to Papua New Guinean and Australian species. The biogeographic reconstruction suggests an Australian origin for the East Asian species that arose through long-distance dispersal during the late Oligocene.