Sonerila

Phonepaseuth, Phongphayboun, Souladeth, Phetlasy, Souvannakhoummane, Keooudone, Vongthavone, Thyraphon & Tagane, Shuichiro, 2021, Two new species of Sonerila Roxb. (Melastomataceae) from Laos, European Journal of Taxonomy 755, pp. 136-148 : 146

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.