| 1 | Hydathodes frequent |
| 1' | Hydathodes absent or sometimes present |
| 2 | Sclerenchyma strands in the rhizome absent or few |
| 2' | Sclerenchyma strands in the rhizome many |
| 3 | Fertile parts similar to sterile part, costa only distinct, margin of fronds with notches regularly present |
| 3' | Fertile parts narrowed or strongly contracted, veins distinct, margin of fronds without notches or notches sporadically present (Philippines and Ternate). |
| 4 | Notches regularly present on margin of lamina |
| 4' | Notches absent or sporadically present on margin of lamina |
| 5 | Vascular strands in the rhizome with bundle sheath fully sclerified (Seram). |
| 5' | Vascular strands in the rhizome with bundle sheath not sclerified |
| 6 | Sori in two rows between adjacent veins (Sulawesi) |
| 6' | Sori in one row between adjacent veins |
| 7 | Sori round, in a single row between costa and margin, rhizome scales strongly dentate or long-ciliate, hydathodes with persistent calcareous scales, fronds usually fully pinnate |
| 7' | Sori in transverse rows or coenosori, rhizome scales remotely and weakly dentate, hydathodes without persistent calcareous scales, fronds simple. |
| 8 | Sori in two rows between adjacent veins |
| 8' | Sori in one row between adjacent veins |
| 9 | Rhizome scales with squarrose, subulate, entire acumen. |
| 9' | Rhizome scales with acumen flat, not squarrose, remotely and weakly to strongly dentate |
| 10 | Fronds dimorphic or monomorphic, linear, fertile to c. 1.2 cm wide, costa only distinct, sori in 1-4 rows between midrib and margin |
| 10' | Fronds monomorphic, fertile fronds over c.1 cm wide, veins distinct, sori in 5 or more rows between midrib and margin |
| 11 | Sori superficial |
| 11' | Sori sunken |
| 12 | Rhizome scales obtuse, whitish, appressed, sclerenchyma strands absent or few. |
| 12' | Rhizome scales acute or contracted to a narrow acumen, brown, spreading or squarrose, sclerenchyma strands many |
| 13 | Rhizome scales contracted to a narrow subulate acumen, sori shallowly sunken. |
| 13' | Rhizome scales obtuse to acute, sori deeply sunken |
| 14 | Fertile parts similar to sterile part |
| 14' | Fertile parts narrowed or strongly contracted |
| 15 | Rhizome scales evenly coloured, 4.8-9 mm long, narrowly acute, vascular strands 4, costa only distinct |
| 15' | Rhizome scales with a lighter margin, to 4 mm long, obtuse to acute, vascular strands 11-14, at least veins distinct |
