Leptochilus, Kaulfuss, 1824

Zhang, Liang, Lu, Ngan Thi, Zhou, Xin-Mao, Zhou, Zhuo, Thepkayson, Khamphanh, Luong, Thien Tam & Zhang, Li-Bing, 2024, Exploring the diversity of the Java fern genus Leptochilus (Polypodiaceae) in the Indo-Burma Biodiversity Hotspot, Phytotaxa 659 (3), pp. 213-235 : 214-216

Key to species of Leptochilus

1. Laminae simple or sometime lamina base lobed...............................................................................................................................2.

- Laminae lobed, pinnatifid, or rarely 2-pinnate to 4-pinnatifid........................................................................................................32.

2. Sori orbicular or elongated, irregularly scattered ..............................................................................................................................3.

- Sori linear, acrostichoid, or elongated then regularly in one row along each side of midrib............................................................4.

3. Petioles and rachises sparely scaly or nearly glabrous, laminae 6–9 × 1.3–1.9 cm ........................................... L. khammouanensis

- Petioles and rachises distinctively scaly, laminae (3.5)8–30 × (0.2) 1.5–5.5 cm ............................................................... L. pteropus

4. Fronds distinctly dimorphic...............................................................................................................................................................5.

- Frond monomorphic or slightly dimorphic .....................................................................................................................................25.

5. Fronds strongly dimorphic, fertile fronds linear, sori fully cover the lower surface.........................................................................6.

- Fronds dimorphic, fertile fronds lanceolate, broadly lanceolate, or ovate, sori shortly linear or long linear .................................17.

6. Sori acrostichoid................................................................................................................................................................................7.

- Sori shortly linear ............................................................................................................................................................................16.

7. Sterile fronds shortly petiolated or sessile.........................................................................................................................................8.

- Sterile fronds distinctly petiolated...................................................................................................................................................13.

8. Sterile fronds less than 10 cm long....................................................................................................................................................9.

- Sterile fronds more than 10 cm long ...............................................................................................................................................11.

9. Apexes of sterile laminae cuneate .................................................................................................................................. L. metallicus

- Apexes of sterile laminae rounded ..................................................................................................................................................10.

10. Length of sterile laminae 3-6 times than lamina width ......................................................................................................... L. minor

- Length of sterile laminae 2-3 times than lamina width .................................................................................................. L. ovatifolius

11. Sterile laminae ca. 0.5 cm wide.............................................................................................................................................. L. wallii

- Sterile laminae more than 1 cm wide ..............................................................................................................................................12.

12. Rhizome sparely scaly with few roots................................................................................................................................ L. axillaris

- Rhizome scaly with many roots ......................................................................................................................................... L. brevipes

13. Laminae lobed .................................................................................................................................................................... L. poilanei

- Laminae entire.................................................................................................................................................................................14.

14. Sterile fronds less than 10 cm long.............................................................................................................................. L. cantoniensis

- Sterile fronds more than 10 cm long ...............................................................................................................................................15. 15. Sterile laminae elliptic or narrowly ovate ....................................................................................................................... L. decurrens

- Sterile laminae lanceolate............................................................................................................................................. L. kachinensis

16. Fertile fronds longer than sterile frond.............................................................................................................................. L. evrardii

- Fertile fronds the same length as, or shorter than sterile frond .............................................................................. L. mengsongensis

17. Fertile fronds shorter than, the same length as, or slight longer than sterile fronds........................................................................18.

- Fertile fronds at least 1.5 times longer than sterile fronds ..............................................................................................................20.

18. Fertile fronds shorter than sterile frond ...................................................................................................................... L. vietnamensis

- Fertile fronds the same length as or slightly longer than sterile frond ............................................................................................19.

19. Laminae thickly chartaceous, petioles of sterile fronds (0.5) 2–5 cm long........................................................................... L. chingii

- Laminae thinly chartaceous, petioles of sterile fronds (0.6)– 1.7 cm long ....................................................... L. luangprabangensis

20. Fertile fronds 1.5 – 2 times longer than sterile fronds.......................................................................................................................21.

- Fertile fronds more than two times longer than sterile fronds.........................................................................................................22.

21. Fertile laminae oblong to broadly oblong ................................................................................................................. L. pedunculatus

- Fertile laminae ovate to narrowly ovate ................................................................................................................................ L. ovatus

22. Fertile laminae narrowly lanceolate .......................................................................................................................... L. sarawakensis

- Fertile laminae broadly lanceolate to ovate.....................................................................................................................................23.

23. Sterile laminae elliptic-lanceolate, base gradually narrowed....................................................................................... L. daklakensis

- Sterile laminae ovate-lanceolate to ovate, base truncate .................................................................................................................24.

24. Fertile laminae 1.5–1.7 cm wide, venation indistinct............................................................................................................... L. locii

- Fertile laminae 3–7 cm wide, venation prominent .................................................................................................................... L. wui

25. Sori interrupted................................................................................................................................................................................26.

- Sori continuous................................................................................................................................................................................27.

26. Circumvascular sheaths present in rhizome, interrupted sori mostly oblong, irregular in shape............................. L. hemionitideus

- Circumvascular sheaths absent in rhizome, interrupted sori shortly linear to linear, regular in shape ..................... L. macrophyllus

27. Venation indistinct ................................................................................................................................................................. L. henryi

- Venation distinct ..............................................................................................................................................................................28.

28. Lamina base with outgrows or lobed...............................................................................................................................................29.

- Lamina base entire...........................................................................................................................................................................31.

29. Petioles distinctively winged......................................................................................................................................... L. hemitomus

- Petioles wingless or slightly winged ...............................................................................................................................................30.

30. Lamina base slightly lobed................................................................................................................................................. L. saxicola

- Laminae distinctly lobed, lobes irregular .................................................................................................................... L. shintenensis

31. Laminae widest at middle or above middle part ................................................................................................................. L. leveillei

- Laminae widest bellow middle part ................................................................................................................................... L. wrightii

32. Laminae 2-pinnate to 4-pinnatifid ............................................................................................................................. L. heterophyllus

- Laminae lobed, pinnatifid................................................................................................................................................................33.

33. Laminae lobed in different extent, from 2- or 3-forked, pedately lobed, to digitately lobed..........................................................34.

- Laminae pinnatifid...........................................................................................................................................................................35.

34. Laminae trilobed, lobe base not narrowed ................................................................................................................... L. ornithopus

- Laminae often digitately lobed, or if trilobed then lobe base distinctly narrowed............................................................ L. digitatus

35. Fronds large, 60–120 cm .................................................................................................................................................................36.

- Fronds less than 60 cm ....................................................................................................................................................................38.

36. Lobes often more than 6 pairs, occurs in mountains with acid soils................................................................................... L. elegans

- Lobes 2 – 6 pairs, occurs in limestone mountains.............................................................................................................................37.

37. Laminae thinly chartaceous.................................................................................................................................... L. sinovietnamica

- Laminae thickly chartaceous ........................................................................................................................................ L. wusugongii

38. Sori oblong, close to the lobe margins ............................................................................................................................. L. oblongus

- Sori linear, rarely oblong, located on main lateral veins between midribs and lobe margins .........................................................39.

39. Rachis broadly winged ....................................................................................................................................................................40.

- Rachis narrowly winged, partial rachis wingless ............................................................................................................................44.

40. Widest of lobes 2.5–4 cm .............................................................................................................................................. L. pothifolius

- Widest of lobes less than 2 cm ........................................................................................................................................................41.

41. Lobes 10 – 12 pairs.................................................................................................................................................... L. dissimilialatus

- Lobes 6 – 9 pairs.................................................................................................................................................................................42

42. Basal most pair of lobes forked................................................................................................................................. L. sanjiangensis

- Basal most pair of lobes not forked.................................................................................................................................................43.

43. Lamia margins flat or sometimes slightly undulate, lobes 12–15 × 1.9–2.4 cm ........................................................ L. neolongipes

- Lamina margins distinctly undulate-repand, lobes 5–12 × 0.9–1.6 cm ........................................................................... L. flexilobus

44. Fronds oblong, lobes 5–8(–14) pairs..............................................................................................................................................45.

- Fronds broad oblong to ovate-deltoid, lobes 1 – 4 pairs ...................................................................................................................46.

45. Sori oblong to shortly linear........................................................................................................................................... L. multilobus

- Sori linear ......................................................................................................................................................................... L. ellipticus

46. Fronds less than 18 cm long ............................................................................................................................................................47.

- Fronds more than 20 cm long..........................................................................................................................................................49.

47. Sori oblong .......................................................................................................................................................... L. bolikhamsaiensis

- Sori shortly linear ............................................................................................................................................................................48. 48. Lobes 1–2 pairs.................................................................................................................................................................... L. gracilis

- Lobes 4–6 pairs............................................................................................................................................................ L. chilangensis

49. Laminae chartaceous to thickly chartaceous ..................................................................................................................... L. longipes

- Laminae herbaceous to thinly chartaceous......................................................................................................................................50.

50. Petioles the same length or slightly longer than laminae ................................................................................................. L. scandens

- Petioles almost as two times as laminae..................................................................................................................... L. pentaphyllus