A synopsis of Lasianthus (Lasiantheae, Rubiaceae) in Thailand and two additional new species Author Napiroon, Tiwtawat 0000-0002-4710-5016 Biology major, Faculty of Science & Technology, Pibulsongkram Rajabhat University, Phitsanulok 65000, Thailand napiroont@gmail.com Author Chayamarit, Kongkanda 0000-0003-1057-6380 The Forest Herbarium (BKF), Department of National Parks, Wildlife and Plant Conservation, Bangkok, 10900, Thailand kchayamarit@gmail.com Author Dawson, Sally 0000-0002-8178-0912 Identification and Naming Department, Royal Botanic Gardens, Kew, Richmond, Surrey, TW 9 3 AE, United Kingdom S.Dawson@kew.org Author Till, Walter 0000-0001-9329-4340 Department of Botany and Biodiversity Research, Faculty of Life Science, University of Vienna, Rennweg 14, A- 1030, Austria walter.till@univie.ac.at Author Balslev, Henrik 0000-0002-7101-7120 Section Ecoinformatics and Biodiversity, Department of Bioscience, Faculty of Science and Technology, Aarhus University, Aarhus 8000, Denmark henrik.balslev@bios.au.dk text Phytotaxa 2020 2020-04-15 439 1 1 38 http://dx.doi.org/10.11646/phytotaxa.439.1.1 journal article 10.11646/phytotaxa.439.1.1 1179-3163 13873503 7. Lasianthus chevalieri Pitard (1924:384) . Type: ― VIETNAM . Annam, Lang-bian, 15 February 1914 , A. J. B. Chevalier 30838 ( holotype P04009921!). = Lasianthus longisepalus Geddes (1928:245) . Type :― THAILAND . Chanthaburi : Khao Soi Dao, 12 December 1924 , A. F. G. Kerr 9632 ( holotype K000777035!; isotype BM001191355 image!, K000777036). T hailand: ―SOUTH-EASTERN. Chanthaburi : Khao Soi Dao Wildlife Sanctuary, 8–9 February 1966 , K. Iwatsuki & N. Fukuoka T7138 (BKF, L), 13 November 1969 , C. F. van Beusekom, T. Smitinand 2203 (BKF, L), 27 November 1979 , T. Shimizu et al. T23760 (BKF, L). Distribution: ― Cambodia (Bokor), Vietnam ( Annam ), Thailand (South-eastern). Ecology: ―Evergreen forest in shaded places at an elevation of 100‒1400 m . Note: ― Lasianthus chevalieri has relatively long calyx lobes and sessile flowers which are easily seen in the field and on herbarium specimens from mainland Southeast Asia. This species is similar to L. capitatus Blume (1827:996) on the southeast Asian archipelago ( Java , Indonesia ) but it differs in having short peduncles (not peduncles up to 2 cm long), 11 pairs of lateral veins (not 7–8 pairs) and relative large flowers; calyx tube 5–6 mm long (not 1–2 mm long), corolla tube 13 mm long (not 10 mm long) and corolla lobes 8 mm long (not 3 mm long).