Paraphyletic Species of Podostemaceae: Cladopus fallax and Polypleurum wallichii Author Kato, Masahiro Department of Botany, National Museum of Nature and Science, Tsukuba 305 - 0005, Japan (e-mail address: mkato 2177 @ yahoo. co. jp) Author Werukamkul, Petcharat Faculty of Science and Technology, Rajamangala University of Technology, Phra Nakhon, Bangkok 10800, Thailand (e-mail address: petcharat. w @ rmutp. ac. th) Author Won, Hyosig Department of Biological Science, Daegu University, Gyungsan, Gyungbuk 712 - 714, Korea (e-mail address: wonhs @ daegu. ac. kr) Author Koi, Satoshi Botanical Gardens, Osaka City University, Katano, Osaka 576 - 0004, Japan (e-mail address: skoi @ sci. osaka-cu. ac. jp) text Phytotaxa 2019 2019-04-10 401 1 33 48 http://dx.doi.org/10.11646/phytotaxa.401.1.3 journal article 3964 10.11646/phytotaxa.401.1.3 aba9dc05-af03-4436-be5a-64c59ebdcbb2 1179-3163 5585849 Cladopus fallax Cladopus fallax was distinguished from other congeners by combined characters. It differs from C . taiensis in the form (surface-viewed and in cross section), surface and number of the bract-segments, from C. nymanii H.Möller in the length of the stamens and the number of ovules, from C. queenslandicus (Domin) C.D.K.Cook & Rutish. in the length of the flowering shoots and the number and form of the bracts, and from C. javanicus M.Kato & Hambali in the length of the flowering shoots, the number of the bracts, and the length of the capsules and capsule stalks ( Table 2 ). In the chloroplast matK tree ( Fig. 1 ), Cladopus was divided into two clades with robust support. One clade (upper in Fig. 1 ) was subdivided into three subclades, i.e. a subclade consisting of C. fallax -1 from Cambodia , C. fallax -2 from Thailand and C . taiensis ; a subclade of C. javanicus , C. nymanii and C. queenslandicus ; and C. fallax - 3 from Cambodia . Cladopus fallax -1 had the same sequence as the Thai specimens of C . taiensis (TL-101, TL-102, TL-604), the two were sister to the other C . taiensis from Cambodia and Thailand , and all were sister to C. fallax -2. Geographically, C. fallax -1 is adjacent to C . taiensis (CAM-07, CAM-14) of Cambodia (4.2 or 12.2 km apart) and far from the Thai populations. The nuclear ITS tree ( Fig. 2 ) showed that there are variations in the ITS regions of C. fallax CAM-13, C. fallax CAM-19 and C. taiensis CAM-14, while uniform in others (e.g. C. fallax CAM-26, C. fallax CAM-41, C. fallax TKF-109, C . taiensis TL-604). The variants of CAM-13 and CAM-19 of C. fallax -1, and CAM-14 of C . taiensis were grouped in each clade, although one C. fallax CAM-13 was isolated. These samples of C. fallax -1 and C. taiensis formed a monophyletic clade, with low support, which was sister to C. fallax -2 and together sister to C. fallax -3. In the combined matK and ITS tree, C. fallax -1 and C . taiensis were monophyletic and sister to C. fallax -2 ( Fig. 3 ). Then, C. fallax -1, C. fallax -2, C. fallax -3 and C . taiensis , together with C. javanicus , were monophyletic.