Revision of the fern genus Diplazium (Polypodiales: Athyriaceae) in Thailand Author Pongkai, Puttamon 0000-0003-0273-1889 Office of National Science Research, National Science Museum, Technopolis, Khlong 5, 39 Moo 3, Khlong Luang, Pathum Thani, 12120, Thailand. & Puttamon. p @ nsm. or. th; https: // orcid. org / 0000 - 0003 - 0273 - 1889 uttamon.p@nsm.or.th Author Zhang, Li-Bing 0000-0002-4905-040X Missouri Botanical Garden, P. O. Box 299, St. Louis, Missouri 63166 - 0299, USA and Chengdu Institute of Biology, Chinese Academy of Sciences, P. O. Box 416, Chengdu, Sichuan 610041, China & Libing. Zhang @ mobot. org; https: // orcid. org / 0000 - 0002 - 4905 - 040 X hang@mobot.org Author Boonkerd, Thaweesakdi 0009-0001-5864-7208 Office of National Science Research, National Science Museum, Technopolis, Khlong 5, 39 Moo 3, Khlong Luang, Pathum Thani, 12120, Thailand. & Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. & bthawees @ googlemail. com; https: // orcid. org / 0009 - 0001 - 5864 - 7208 bthawees@googlemail.com Author Pollawatn, Rossarin 0000-0001-6798-7274 Office of National Science Research, National Science Museum, Technopolis, Khlong 5, 39 Moo 3, Khlong Luang, Pathum Thani, 12120, Thailand. & Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. & Office of National Science Research, National Science Museum, Technopolis, Khlong 5, 39 Moo 3, Khlong Luang, Pathum Thani, 12120, Thailand. & Rossarin. p @ chula. ac. th; https: // orcid. org / 0000 - 0001 - 6798 - 7274 * Corresponding authors: Puttamon. p @ nsm. or. th; Libing. Zhang @ mobot. org & Office of National Science Research, National Science Museum, Technopolis, Khlong 5, 39 Moo 3, Khlong Luang, Pathum Thani, 12120, Thailand. ossarin.p@chula.ac.th text Phytotaxa 2023 2023-12-22 631 1 1 69 https://phytotaxa.mapress.com/pt/article/download/phytotaxa.631.1.1/51384 journal article 10.11646/phytotaxa.631.1.1 1179-3163 10422862 23. Diplazium siamense C. Christensen (1931: 332) . Fig. 29 . Type : THAILAND . Chiang Mai , Summit of Doi Chom Cheng , 1500–1650 m , Rock 1507 ( holotype GH ) . Plants terrestrial. Stems erect, 3–4 cm diameter, apex densely scaly; scales 10.0–12.0 × 1.0– 1.5 mm , linear, long tail at apex, brown, margin thick and toothed. Fronds 0.85–1.2 m , pinnate; petioles 30–50 cm , 5–8 cm diameter, deep green, densely scaly at base. Laminae up to 55–70 × 30–40 cm , oblong in outline; terminal pinna distinct, 18–20 cm long, gradually narrowing towards attenuate apex, margin lobed; lateral pinnae 6–8 pairs, alternate, 20–25 × 3.5–4.0 cm, linear-oblong, apex acuminate, base subtruncate, margin lobed; lobe half way to midrib, stalked; stalks 1.5–2.0 cm; rachis and costa often bearing minute scales; veins free, pinnate, veinlets 8–9 pairs, mostly simple. Sori 3–4 mm , elongate along veinlets, close to main vein. Spores monolete, 35–40 × 22.5–27.5 µm, bilateral, concavo-convex to plano-convex, perispore present; ornamentation: prominent wing folds. Thailand : —NORTHERN: Chiang Mai (Doi Suthep, Mae Wang), Chiang Rai (Doi Pacho), Phitsanulok (Phu Hin Rong Kla, Phu Rom Rot), Nan (Doi Phuka, Khao Nok), Phrae (Mae Sai); NORTH-EASTERN: Phetchabun (Phu Miang), Loei (Na Haew, Phu Luang, Phu Suan Sai) . Distribution: — China . Ecology: —On humus-rich mountain slopes in mixed or evergreen forests at 850–1,500 m elev. Specimens Examined:— THAILAND . Phitsanulok , Phu Hin Rong kla, AR 69 (BCU); no locality, D.J. Middleton et al. 4926 (PSU); Loei , Phu Suan Sai, D.J. Middleton et al. 5115 (PSU); loei, Phu Luang, E. Hennipman 3621 (L); no locality, H. Koyama , H. Terao & T. Wongprasert T33676 (BKF); Chiang Mai , Mae Wang, J.F. Maxwell 03-99 (L); Chiang Mai , Doi Suthep, J.F. Maxwell 87-791 (L); K. Iwatsuki T4462 (BKF, L); Prae, Mae Sai, K. Winit 959 (BKF); Phitsanulok , Phu Hin Rong kla, P. Pongkai 16 (BCU); ibis., P. Pongkai 17 (BCU); Chiang Rai , Doi Pacho, K. Iwatsuki & N. Fukuoka T3681 (L); Nan , Doi Phuka, P. Pongkai 9 (BCU); Nan , Doi Phuka, P. Pongkai 148 (BCU); Chiang Mai , Doi Inthanon, P. Srisanga & P. Suksathan 3269 (QBG); Nan , Doi Phuka, T. Boonkerd 1574 (BCU); Petchchabun, Phu miang; T. Shimizu et al. T11367 (L); Nan , Khao Nok, W. La-ongsri et al. 1987 (QBG); Loei , Na Haew, W. Nanakorn 3875 (QBG).