1Hydathodes frequent
1'Hydathodes absent or sometimes present
2Sclerenchyma strands in the rhizome absent or few
2'Sclerenchyma strands in the rhizome many
3Fertile 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).
4Notches regularly present on margin of lamina
4'Notches absent or sporadically present on margin of lamina
5Vascular strands in the rhizome with bundle sheath fully sclerified (Seram).
5'Vascular strands in the rhizome with bundle sheath not sclerified
6Sori in two rows between adjacent veins (Sulawesi)
6'Sori in one row between adjacent veins
7Sori 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.
8Sori in two rows between adjacent veins
8'Sori in one row between adjacent veins
9Rhizome scales with squarrose, subulate, entire acumen.
9'Rhizome scales with acumen flat, not squarrose, remotely and weakly to strongly dentate
10Fronds 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
11Sori superficial
11'Sori sunken
12Rhizome 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
13Rhizome scales contracted to a narrow subulate acumen, sori shallowly sunken.
13'Rhizome scales obtuse to acute, sori deeply sunken
14Fertile parts similar to sterile part
14'Fertile parts narrowed or strongly contracted
15Rhizome 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