Lanonia, Henderson & Bacon, 2011

Henderson, Andrew & D ựng, Nguy ễn Qu ốc, 2022, A revision of Lanonia (Arecaceae, Coryphoideae, Livistoninae), Phytotaxa 532 (3), pp. 209-245 : 220-221

Key to the species of Lanonia

1. Ligules papery, not disintegrating into fibers; sheaths and proximalmost part of petioles with dense, flat, black scales; petiole thorns usually stout, reddish-brown or dark brown, some bifid or often some in pairs, on proximalmost part of petiole ...............2.

- Ligules soon disintegrating into fibers; sheaths and proximalmost part of petioles with scattered, brown scales, or without scales; petiole thorns usually poorly developed, brown or black, more or less regularly arranged on proximalmost part of petiole, rarely stout reddish-brown or dark brown, some bifid or in pairs ...............................................................................................................6.

2. Costas continuous to apex of leaf, without an abaxial pulvinus; segments 5; rachillae densely covered with erect, branched, translucent hairs; southern Vietnam in Kon Tum, Kon Plong district......................................................................... L. manglaensis

- Costas not continuous to apex of leaf, with an abaxial pulvinus at the apex; segments 6-20; rachillae sparsely to moderately covered with short, mostly simple, brownish hairs ...........................................................................................................................3.

3. Hastulas raised, triangular, infolded; rachis bracts flattened, splitting apically and laterally, usually densely brown tomentose; southern Vietnam in Khanh Hoa, Hon Ba Nature Reserve ........................................................................................... L. honbaensis

- Hastulas flat, rounded, not infolded; rachis bracts narrowly tubular, splitting apically, not or sparsely tomentose .........................4.

4. Segments (on dried specimens) with straight margins; rachillae not filiform; southern Vietnam in Khanh Hoa ............. L. montana

- Segments (on dried specimens) with ruffled margins, rarely straight; rachillae filiform..................................................................5.

5. Segments (on dried specimens) with ruffled margins; ligules 32.9(29.5–40.0) cm long; middle segments 31.0(24.5–37.5) cm long; southern Vietnam in Khanh Hoa, Hon Ba Nature Reserve ............................................................................................. L. tenuisecta

- Segments (on dried specimens) with straight or ruffled margins; ligules 10.4(8.0–13.0) cm long; middle segments 20.0(16.2–24.0) cm long; southern Vietnam in Dak Lac, Khanh Hoa, and Ninh Thuan ......................................................................... L. hexasepala

6. Sheaths and proximalmost part of petioles without scales; leaf segments without minute, reddish-brown scales abaxially; central Vietnam in Quang Ngai, Ba To District ........................................................................................................................... L. batoensis

- Sheaths and proximalmost part of petioles with scattered, brown scales; leaf segments with minute, reddish-brown scales abaxially ............................................................................................................................................................................................7.

7. Leaf segments mottled; rachillae thick and ribbed; pistillate rachillae 2.8(1.8-3.4) mm diameter...................................................8.

- Leaf segments not mottled; rachillae not thick and ribbed; pistillate rachillae 1.4(0.4-2.5) mm diameter.......................................9.

8. Costas 5.8(3.5–8.0) cm long, triangular, with the numerous segments free almost to the base; rachis bracts not tattering, usually densely brown tomentose; central Vietnam in Da Nang City, Ba Na-Nui Chua Nature Reserve ........................................ L. acaulis

- Costas 14.1(8.5–24.0) cm long, narrow, with the numerous segments free to the base except the middle pair joined at their bases; rachis bracts strongly ribbed and tattering along the ribs; southern China in Guangxi and Yunnan and northern Vietnam in Bac Kan, Ha Giang, Lao Cai, Nghe An, Phu Tho, Quang Ninh, Thanh Hoa, Tuyen Quang, and Vinh Phuc ................................ L. dasyantha

9. Segments (on dried specimens) with ruffled margins; rachillae filiform; southern Vietnam in Gia Lai and Kon Tum ...................... ...................................................................................................................................................................................... L. kontumensis

- Segments (on dried specimens) with straight margins; rachillae not filiform.................................................................................10.

10. Costas narrow, with a pulvinus at the apex abaxially, with the numerous segments free to the base except the middle pair joined at their bases; rachis bracts flattened, splitting apically and laterally, almost woody and scarcely tomentose...................................11.

- Costas triangular, with a pulvinus at the apex abaxially, with the numerous (rarely few) segments free to the base, or costas narrow, with a pulvinus at the apex abaxially, with the few segments free except central pair joined at their bases; rachis bracts tubular, splitting apically and laterally, becoming fibrous at the apex, covered with scattered, reddish-brown hairs, or rarely rachis bracts flattened, splitting apically and laterally, usually densely brown tomentose ..................................................................................13.

11. Hastulas raised, triangular, infolded; southern Vietnam in Ninh Thuan, Nui Chua National Park............................. L. nuichuaensis

- Hastulas flat, rounded, not infolded ................................................................................................................................................12.

12. Middle segments 37.5 cm long, 8.7 cm wide at the apex; apices of middle segments with adaxial splits much deeper than abaxial ones; southern Vietnam in Khanh Hoa, Hon Heo ........................................................................................................ L. honheoensis

- Middle segments 48.3(33.5–57.5) cm long, 6.3(4.5–7.5) cm wide at the apex; apices of middle segments with adaxial splits not much deeper than abaxial ones;.southern Vietnam in Khanh Hoa ..................................................................................... L. poilanei

13. Petiole thorns usually stout, reddish-brown or dark brown, some bifid or often some in pairs, on proximalmost part of petiole; hastulas flat, rounded, not infolded; southern Vietnam in Gia Lai ................................................................................. L. gialaiensis

- Petiole thorns usually poorly developed, brown or black, more or less regularly arranged on proximalmost part of petiole; hastulas raised, triangular, infolded...............................................................................................................................................................14.

14. Costas 3.0(1.6–4.5) cm long, triangular, with a pulvinus at the apex abaxially, with the numerous segments free almost to the base; segments 19(13–29) per leaf ...........................................................................................................................................................15.

- Costas 10.6(6.0-9.8) cm long, narrow, with a pulvinus at the apex abaxially, with the few segments free except the middle pair joined at their bases; segments 7(6-9) per leaf ................................................................................................................................16.

15. Rachillae densely covered with wooly, much branched, reddish-brown hairs; fruits white, whitish, or dull yellow; central Laos in Bolikhamsay and central Vietnam in Ha Tinh, Quang Binh, Quang Nam, Quang Tri, Thua Thien-Hue, and Da Nang City ............. ........................................................................................................................................................................................... L. centralis

- Rachillae sparsely to moderately covered with short, mostly simple, brownish hairs; fruits red; China, Hainan … L. hainanensis

16. Fruits ellipsoid, orange, with uneven, ridged surfaces; southern Vietnam in Khanh Hoa .............................................. L. verrucosa

- Fruits globose, red, pink, or red to black, with smooth surfaces.....................................................................................................17.

17. Hastulas flat, rounded, not infolded; central Vietnam in Thua Thien-Hue in Bac Ma National Park and Da Nang City in Ba Na-Nui Chua Nature Reserve ....................................................................................................................................................... L. magalonii

- Hastulas raised, triangular, infolded ................................................................................................................................................18.

18. Rachis bracts tubular, splitting apically and laterally, becoming fibrous at the apex, covered with scattered, reddish-brown hairs; northern Vietnam in Hoa Binh, Ninh Binh, Phu To, and Son La .................................................................................... L. calciphila

- Rachis bracts flattened, splitting apically and laterally, usually densely brown tomentose; Indonesia, Java, Ujung Kulon National Park...................................................................................................................................................................................... L. gracilis