Chassalia Comm. ex Poir.

Yu, Tian Yi, Turner, Ian M. & Cheek, Martin, 2021, Revision of Chassalia (Rubiaceae-Rubioideae-Palicoureeae) in Borneo, with 14 new species, European Journal of Taxonomy 738, pp. 1-60 : 7-8

Key to species of Chassalia Comm. ex Poir. in Borneo

1. Plant epiphytic, fruit narrowly ellipsoid, 3–4 mm wide, pyrene dorsal surface with a central groove, pyrene ventral surface with a central groove and ridge as high as plane of endocarpal outgrowth ............................................................................ Chassalia javanica (Blume) I.M.Turner

– Plant terrestrial (sometimes epiphytic in C. muluensis ), fruit ellipsoid or globose,> 5 mm wide, pyrene dorsal surface with 1 or 2 central longitudinal crests, pyrene ventral surface with a central ridge lower than the plane of the endocarpal outgrowth .................................................................. 2

2. Stipules bilobed to the base, apex of lobes caudate; inflorescences with 2–3 toothed stipule-like bracts usually <5 mm long, corolla tubes curved, usually winged; pyrene dorsal surface with 1 central longitudinal crest ...................................... Chassalia curviflora (Wall.) Thwaites complex

– Stipule margins entire, incised or 1–3 toothed, usually not bilobed, if bilobed then by <¼ the length; inflorescences with bracts> 5 mm long at secondary peduncle node and each capitulum; corolla tubes not curved or winged; pyrene dorsal surface with 2 central, adjacent longitudinal crests ...... 3

3. Herb or small shrub, 25–30 cm tall; fruit white when ripe ...... Chassalia muscicola T.Y.Yu sp. nov.

– Herb, shrub or tree, taller than 40 cm; fruit bluish green, blue, purplish green or dark purple when ripe .................................................................................................................................................... 4

4. Abaxial surface of leaves with midrib and secondary nerves densely pubescent .............................. ............................................................................... Chassalia psychotriformis I.M.Turner nom. nov.

– Abaxial surface of leaves with midrib and secondary nerves glabrous ............................................ 5

5. Inflorescences longer than longest leaves (Mount Kinabalu) ..... Chassalia longipes T.Y.Yu sp. nov.

– Inflorescences shorter than longest leaves ........................................................................................ 6

6. Stem, petiole, nerves of leaves abaxially and peduncle blackish purple, corolla usually purplish white ................................................................................... Chassalia atropurpurea T.Y.Yu sp. nov.

– Stem and petiole green or purplish green, nerves of leaves abaxially and peduncle green, corolla white, cream white or yellowish white ............................................................................................. 7

7. Bracts of capitulum not covering top of calyx at anthesis (Kinabalu) ............................................... ............................................................................................ Chassalia kinabaluensis T.Y.Yu sp. nov.

– Bracts of capitulum covering top of calyx at anthesis ...................................................................... 8

8. Leaf-blades lanceolate to narrowly elliptic, 5–10 times as long as wide ......................................... 9

– Leaf-blades elliptic, oblong, obovate or ovate, 2–4 times as long as wide .....................................11

9. Bracts of capitulum 10–12 × 5–10 mm, usually equal to or longer than flower buds; fruits 10–12 mm long (Kuching) ...................................................................... Chassalia macrocarpa T.Y.Yu sp. nov.

– Bracts of capitulum 3–6 × 2–6 mm, usually shorter than flower buds; fruits <8 mm long ........... 10

10. Leaf-blades elliptic or oblanceolate, 5–7 times as long as wide (Kuching) ....................................... ................................................................................................... Chassalia lancifolia T.Y.Yu sp. nov.

– Leaf-blades narrowly lanceolate, 8–10 times as long as wide (Kuching) .......................................... ............................................................................................. Chassalia lancifolioides T.Y.Yu sp. nov.

11. Longest leaf-blades usually longer than 25 cm, inflorescences <6 cm long, peduncle <4 cm long .. ......................................................................................................................................................... 12

– Longest leaf-blades usually shorter than 20 cm, inflorescences Ẑ 6 cm long, peduncle> 4 cm long. ......................................................................................................................................................... 14

12. Bracts of capitulum covering fruits (Sarwak, Sabah and Brunei) ...................................................... ................................................................................................ Chassalia involucrata T.Y.Yu sp. nov.

– Bracts of capitulum not covering fruits .......................................................................................... 13

13. Stems 5–12 mm diameter, internodes 3–6 cm long (Sabah: Tambunan and Ranau) .......................... ..................................................................................................... Chassalia calamus T.Y.Yu sp. nov.

– Stems 4–6(–8) mm diameter, internodes 1–3 cm long (Sabah: Kinabalu) ......................................... .................................................................................................... Chassalia beamanii T.Y.Yu sp. nov.

14. Rachis and branches of inflorescence <4 mm long or absent, capitulum condensed into 1 head .. 15

– Rachis and branches of inflorescence> 10 mm long, capitulum not condensed into 1 head ......... 16

15. Plant only producing 1 flowering branch on old stems, bracts of capitulum Ξ 5 mm long ................ ............................................................................................................ Chassalia blumeana Govaerts

– Plant usually producing 2 flowering branches on old stems, bracts of capitulum Ẑ 10 mm long ....... ....................................................................................................... Chassalia ramosa T.Y.Yu sp. nov.

16. Peduncle Ξ 1 cm long, bracts of capitulum longer than flowers and fruits ......................................... ........................................................................................................ Chassalia chewii T.Y.Yu sp. nov.

– Peduncle> 1 cm long, bracts of capitulum shorter than flowers and fruits .................................... 17

17. Inflorescences usually longer than first pair of leaves; secondary nerves 16–18 on each side of the midrib (Gunung Mulu endemic) .............................................. Chassalia muluensis T.Y.Yu sp. nov.

– Inflorescences usually shorter than first pair of leaves; secondary nerves 8–14 on each side of the midrib (Sabah and Sarawak) ..................................................... Chassalia northiana T.Y.Yu sp. nov.