Polyalthia, Blume

Wiya, Chattida, Damthongdee, Anissara, Chanthamrong, Kithisak, Ue-Aree, Phasit & Chaowasku, Tanawat, 2025, Uncovering five new species of Polyalthia (Annonaceae, Miliuseae) from Thailand: molecular and morphological congruence, European Journal of Taxonomy 1022, pp. 243-276 : 265-267

Key to the species of Polyalthia in Thailand belonging to clade 2

1. Petals of both whorls subequal, (rather) thick and fleshy ................................................................. 2

– Petals of both whorls unequal, inner petals (rather) thick and fleshy, outer petals markedly smaller, thinner and less fleshy ....................................................................................................................... 3

2. Flowers sessile or subsessile; carpels 6–12(–20) per flower; ovules 2 per ovary; monocarps dark red in vivo at maturity, sessile or subsessile ............................................................................................. .................... P. debilis (Pierre) Finet & Gagnep. ( Finet & Gagnepain 1906; basionym: Pierre 1881)

– Flowers pedicellate (pedicels 7.5–14.5 mm long); carpels 4 per flower; ovules 4–6 per ovary; monocarps yellow in vivo at maturity, stipitate (stipes 6.0–8.0 mm long) ......................................... ........................................................ P. suthepensis Wiya & Chaowasku ( Wiya & Chaowasku 2021)

3. Carpels 1–2 per flower; ovules 3–8 per ovary ................................................ P. cambodica (Finet & Gagnep.) Wiya & Chaowasku ( Wiya & Chaowasku 2021; basionym: Finet & Gagnepain 1906)

– Carpels ≥ 3 per flower; ovule(s) usually 1–2 per ovary .................................................................... 4

4. Flowering pedicels < 13 mm long ..................................................................................................... 5

– Flowering pedicels ≥ 13 mm long ................................................................................................... 13

5. Flowering pedicels < 3 mm long; apex of outer petals obtuse to rounded; carpels 3 per flower ........ .............................................................. P. miliusifolia Wiya, Chanthamrong & Chaowasku sp. nov.

– Flowering pedicels ≥ 3 mm long; apex of outer petals acute to acute-obtuse; carpels ≥ 4 per flower ........................................................................................................................................................... 6

6. Outer petals < 3 mm long .................................................................................................................. 7

– Outer petals ≥ 3 mm long .................................................................................................................. 8

7. Leaf apex acuminate; flowering pedicels 4.0–6.0 mm long; carpels 10–15 per flower ..................... ....................................... P. chantaranothaii Bunchalee & Chalermglin (in Bunchalee et al. 2021b)

– Leaf apex usually acute to acute-obtuse; flowering pedicels 6.5–8.0 mm long; carpels 16–22 per flower ............................................................. P. chiangmaica Wiya, Damth. & Chaowasku sp. nov.

8. Inner petals obovate ......... P. chalermglinii Bunchalee & D.M.Johnson (in Bunchalee et al. 2021b)

– Inner petals (narrowly) ovate, (narrowly) ovate-elliptic or elliptic-oblong ...................................... 9

9. Carpels 25–35 per flower ............ P. khaoyaiensis Bunchalee & Chantar. (in Bunchalee et al. 2019)

– Carpels <25 per flower ................................................................................................................... 10

10. Base of inner petals usually orange-red in vivo at maturity; monocarps subsessile .......................... ......................... P. kanchanaburiana Khumch. & Thongp. (Khumchompoo & Thongpakdee 2005)

– Base of inner petals ± pale yellow in vivo at maturity; monocarps stipitate (stipes 3.0–7.0 mm long) .................................................................................................................................................11

11. Outer petals 3.0– 3.5 mm long; carpels 18–20 per flower ................................................................... .......................................... P. khaosokensis Bunchalee, Leerat. & Sinbumr. ( Bunchalee et al. 2025)

– Outer petals> 3.5 mm long; carpels <18 per flower ...................................................................... 12

12. Young twigs sparsely hairy; leaf blades chartaceous-subcoriaceous, acumen (12.0–)16.0–26.0 mm long ........................................................... P. acuminatissima Wiya, Damth. & Chaowasku sp. nov.

– Young twigs densely hairy; leaf blades chartaceous, acumen 6.0–9.0 mm long ................................ ............................................................................. P. esanensis Wiya, Damth. & Chaowasku sp. nov.

13. Leaf blades subcoriaceous, apex usually caudate-acuminate; carpels>40 per flower ....................... ............................................................ P. maxwelliana Wiya, Chanthamrong & Chaowasku sp. nov.

– Leaf blades chartaceous, apex acute to rounded-obtuse; carpels ≤ 40 per flower .......................... 14

14. Bark (of large stems) corky; carpels 25–40 per flower; monocarps ± black in vivo at maturity ........ ...................................... P. suberosa (Roxb.) Thwaites ( Thwaites 1864; basionym: Roxburgh 1795)

– Bark not corky; carpels <25 per flower; monocarps red in vivo at maturity ..................................... .......................................................... P. intermedia (Pierre) Bân ( Bân 2000; basionym: Pierre 1881)