| 1 | Sori irregularly scattered on the lamina surface |
| 1' | Sori more or less regularly spaced, in a single row between costa and margin, or in 1 or 2 rows between the lateral veins |
| 2 | Lamina pinnate |
| 2' | Lamina simple or pinnatifid |
| 3 | Rhizome white waxy, terete, with scattered sclerenchyma strands, connecting veins forming several ± equally sized areoles between two adjacent veins, sometimes forming one row of small primary costal areoles |
| 3' | Rhizome not white waxy, dorsiventrally flattened, without scattered sclerenchyma strands, connecting veins forming one row of large areoles parallel to the costa, bordered by several smaller areoles; costal areole, if present, formed by smaller veins |
| 4 | Rhizome without sclerified circumvascular sheaths, sori generally absent from costal areoles |
| 4' | Rhizome with sclerified circumvascular sheaths, sori generally present in costal areoles |
| 5 | Lamina pinnatifid |
| 5' | Lamina simple |
| 6 | Lamina 20-40 cm long, thin-herbaceous, undersurface without acicular hairs, longest lobes widest at base or below middle, 1.3-2.5 cm wide |
| 6' | Lamina 45-70 cm long, herbaceous, undersurface with acicular hairs, longest lobes widest about or above middle, 5-6 cm wide |
| 7 | Stipe 0.5-1.5 mm thick, roots sparsely set, lamina thin-herbaceous, smaller veins more or less immersed and vague |
| 7' | Stipe 3-5 mm thick, roots densely set, lamina herbaceous, smaller veins prominent and distinct |
| 8 | Rhizome white waxy |
| 8' | Rhizome not white waxy |
| 9 | Scales 0.2-0.3 mm wide |
| 9' | Scales 0.5-1.4 mm wide |
| 10 | Scales 2-7 mm long, cells elongated, lamina herbaceous. |
| 10' | Scales 0.5-1.3 mm long, cells small, more or less isodiametric, lamina thin-her-baceous or membranaceous |
| 11 | Sori in a single row between costa and margin, generally close to the costa, at most halfway to the margin |
| 11' | Sori in several rows between costa and margin |
| 12 | Sori deeply sunken, visible as protrusions on the upper surface, scales pseudopeltate, the apical lamina-lobe 2.5-6.5 cm wide |
| 12' | Sori superficial or slightly immersed, scales peltate, the apical lamina-lobe 0.9-1.7 cm wide |
| 13 | Scales peltate, appressed or slightly spreading |
| 13' | Scales basifixed or pseudopeltate, distinctly spreading |
| 14 | Lamina simple, scales distinctly spreading |
| 14' | Lamina pinnatifid to pinnate, scales appressed or slightly spreading |
| 15 | Scales narrowly ovate or triangular, margin usually intact, denticulate, lamina base cuneate to cuneate-angustate, not decurrent into a long wing. |
| 15' | Scales round or elliptic, entire, often with eroded margin, lamina base narrowly angustate, decurrent into a long wing |
| 16 | Rhizome without sclerified circumvascular sheaths, lamina pinnatifid throughout, index 1.5-2, connecting veins 2-4, sori 1.6-3 mm diam. |
| 16' | Rhizome with sclerified circumvascular sheaths, lamina pinnate at base, index 1.3, connecting veins 7, sori 1 mm diam. |
