Two new species of Sonerila Roxb. (Melastomataceae) from Laos Author Phonepaseuth, Phongphayboun Faculty of Environmental Sciences, National University of Laos, Dongdok Campus, Xaythany District, Vientiane Capital, Laos. p.phonepaseuth@nuol.edu.la Author Souladeth, Phetlasy p.souladeth@nuol.edu.la Author Souvannakhoummane, Keooudone Centre for Development and Environment, Lao Country Office, Unit 11, # 136, Simuang Road, Hom 1, P. O. Box 1438, Ban Phapo, Vientiane, Laos. keooudone1988@gmail.com Author Vongthavone, Thyraphon Association for Community Development (ACD), Salavan Province, Laos. thyraphon@gmail.com Author Tagane, Shuichiro The Kagoshima University Museum, Kagoshima University, Kagoshima, Japan. stagane29@gmail.com text European Journal of Taxonomy 2021 2021-06-22 755 136 148 http://dx.doi.org/10.5852/ejt.2021.755.1403 journal article 5991 10.5852/ejt.2021.755.1403 4e0dadd2-0530-4ab7-8314-3a0b1576ea27 2118-9773 5012980 Key to the species of Sonerila in Laos 1. Acaulescent herb without evident erect stems above ground or with a very short rhizomatous stem; leaves forming a rosette .................................................................................................................... 6 – Caulescent herb with evident stems above ground; leaves distributed along the stem or branchlets ........................................................................................................................................................... 2 2. Opposite leaves on stems isomorphic; lamina linear to elliptic-oblong, less than 3 cm long, acute, cuneate to attenuate at base ............................................................................................................... 3 – Opposite leaves on stems dimorphic; lamina ovate, more than 3 cm long, cordate to rounded at base ................................................................................................................................................... 4 3. Stem and branchlets glandular-pilose or puberulous; lamina setose on both surfaces ........................ ................................................................................................................................ 7. S. tenera Royle – Stem and branchlets glabrous; lamina glabrous to glabrescent on both surfaces ................................ ....................................................................................................... 4. S. neodriessenioides C.Hansen 4. Petiole glabrous, succulent and winged ........................................................ 5. S. plagiocardia Diels – Petiole hairy, not winged .................................................................................................................. 5 5. Lamina glabrous except veins abaxially, margin glabrous; petiole 0.3–1.2 cm long .......................... .................................................................................................................... 3. S. lecomtei Guillaumin – Lamina covered with long brown hairs, margin ciliate; petiole (0.6–) 1–3.5 cm long ........................ ................................................................................................9. S. yunnanensis Jeffrey ex W.W.Sm. 6. Lamina less than 1.4 cm long; inflorescence 1-flowered .................................................................... .....................................................................................1. S. bolavenensis Soulad., Tagane & Suddee – Lamina more than 3 cm long; inflorescence 2- to many-flowered ................................................... 7 7. Lamina elliptic-oblong, ovate-elliptic, base acute, cuneate to attenuate; hypanthium 8–9 mm long ...........................................................................2. S. erectifolia Phonep., Soulad. & Tagane sp. nov. – Lamina ovate to rounded, base cordate; hypanthium less than 6 mm long ...................................... 8 8. Lateral primary veins 3 pairs; inflorescence 2–3-flowered; hypanthium glabrous ............................. ...................................................................................... 8. S. vatphouensis Munzinger & C.V.Martin – Lateral primary veins 4–5 pairs; inflorescence 20–25-flowered; hypanthium sparsely covered with villous hairs .................................................................... 6. S. souvannii Phonep. & Soulad. sp. nov.