| 1 | Indusium present. |
| 1' | Indusium lacking. |
| 2 | Stipe bearing many bristles 10-20 mm long, spreading at right angles, surface of bristles covered with dark setae. |
| 2' | Stipe lacking such bristles. |
| 3 | Slender hairs 1 mm long abundant on costae, costules and veins beneath. |
| 3' | Such hairs lacking; at most much shorter hairs present towards apices of pinnules. |
| 4 | Largest pinnules 90-120 by 16-20 mm; costae not densely scaly; no bullate scales on costae and costules |
| 4' | Largest pinnules 50 by 10 mm; costae densely scaly; bullate scales present on costules. |
| 5 | Scales of stipe-base to 50 mm or more long, shining medium brown, rigid, edges bearing sparse rather long concolorous setae. Lamina very rigid, edges strongly reflexed and inrolled. |
| 5' | Scales on stipe-base mostly shorter, often not rigid and pale, edges mostly bearing close dark setae. Edges of lamina rarely much reflexed and then not inrolled. |
| 6 | Pinnules to 30 mm long. Scales on stipe-base 2 mm wide; pinna-rachis rather persistently covered with a feit of small pale fringed scales; scales on costules bearing pale crisped marginal hairs. |
| 6' | Pinnules 45-80 mm long. Scales on stipe-base 3-5 mm wide; pinna-rachis not persistently or densely so covered; scales on costules often bearing long dark setae. |
| 7 | Stipe bearing many dark shining spines 3-6 mm long. Pinnules to 80 mm long. |
| 7' | Stipe lacking spines. Pinnules commonly to 45 mm long |
| 8 | Upper part of stipe and all rachises finely and very closely warty; bullate scales always present on costules. |
| 8' | Upper part of stipe and rachises thorny or conspicuously warty, warts not very fine and close; bullate scales present or not. |
| 9 | Long pale hairs normally lacking on lower surface of costae and costules, present on upper surface of costules; no setiferous scales on costae |
| 9' | Long pale hairs always rather abundant distally on lower surface of costae and costules, lacking or very few on upper surface of costules; setiferous scales present at least near base of costae. |
| 10 | Veins commonly 15 pairs; setiferous scales on costae of lower pinnules only. |
| 10' | Veins 9-12 pairs; setiferous scales always abundant on costae |
| 11 | Scales on costules abundant, copiously fringed with long crisped hairs which become entangled and form a woolly covering. |
| 11' | Scales on costules not thus fringed. |
| 12 | Scales on costules not setiferous; lamina-segments much curved forwards when dry; hairs on upper surface of pinna-rachis pale |
| 12' | Scales at bases of costules bearing many long dark setae; lamina-segments spreading at right angles to costa; hairs on upper surface of pinna-rachis dark |
| 13 | Bullate scales present on lower surface of costae and or costules. |
| 13' | Bullate scales lacking on lower surface of costae and costules. |
| 14 | Bullate scales present on lower surface of veins. |
| 14' | Bullate scales lacking on lower surface of veins. |
| 15 | Copious long hairs also on lower surface of veins |
| 15' | Long hairs lacking on lower surface of veins, or only at vein-tips. |
| 16 | Pinna-rachis closely warty, warts dark; pinnules to 13 mm wide. Luzon. |
| 16' | Pinna-rachis sparsely thorny or warty; pinnules 15-25 mm wide. New Guinea. |
| 17 | Stipe conspicuously spiny; pale hairs on lower surface of costae few or lacking. |
| 17' | Stipe warty; pale hairs abundant on lower surface of distal half of costae and on costules. |
| 18 | Costae copiously scaly throughout, with small pale-fringed scales as well as elongate setiferous ones; bullate scales not setiferous |
| 18' | Costae rather sparsely scaly, small pale-fringed scales lacking; bullate scales on costules setiferous |
| 19 | Pale erect hairs abundant on lower surface of veins. |
| 19' | Pale erect hairs absent or rare (near apices of segments) on lower surface of veins. |
| 20 | Costae bearing many much-setiferous scales; pinnules to 20 mm wide. |
| 20' | Costae bearing very few scales; pinnules commonly 20-30 mm wide. |
| 21 | Veins flat or impressed beneath; costular scales with long brown setae. |
| 21' | Veins much raised beneath; costular scales with short dark setae. |
| 22 | Stipe-scales pale, 40-50 mm long, 4-5 mm wide at base, distal half very narrow; costular scales broad, pale, flat, short-setiferous or short-fringed |
| 22' | Stipe-scales otherwise; costular scales (if present) narrower, bearing long setae. |
| 23 | Setiferous scales abundant on costae; small scales present on lower surface of veins; no stout hairs on lower surface of costae. |
| 23' | Setiferous scales lacking or rare on lower surface of costae of mature fronds; no scales on lower surface of veins; stout pale hairs present near apices on lower surface of costae. |
| 24 | Stipe-scales 5 mm wide. Pinnules to 25 mm wide. Veins 13-15 pairs. |
| 24' | Stipe-scales 2 mm wide. Pinnules to 35 mm wide. Veins to 20 pairs. |
