KEY TO THE SPECIES OF BORNEO

1Fertile parts strongly contracted, much narrower than fertile parts
1'Fertile parts similar to sterile part, slightly narrowed or both equally narrow, gramineous
2Sori superficial
2'Sori sunken
3Margin of sterile fronds without notches, rhizome scales pseudopeltate, hydathodes absent, costa only distinct
3'Margin of sterile fronds with notches regularly present, rhizome scales peltate, hydathodes sometimes present, or frequent, at least veins distinct
4Sori round, sterile lamina 10.5 cm long, notches in fertile fronds regularly present (‘kamborangana’)
4'Sori elongate, forming coenosori, sterile lamina 2-5.5 cm long, notches in fertile fronds absent
5Sori forming longitudinal coenosori
5'Sori separate or in transverse coenosori
6Hydathodes frequent, margin of sterile fronds without notches.
6'Hydathodes absent, margin of sterile fronds with notches sporadically to regularly present
7Rhizome with 11-14 vascular strands, rhizome scales with a lighter margin, at least veins distinct
7'Rhizome with 4 vascular strands, rhizome scales evenly coloured, costa only distinct
8Hydathodes frequent
8'Hydathodes absent or infrequent
9Fertile fronds trilobed, pinnatifid or pinnate
9'Fronds simple
10Hydathodes covered with persistent calcareous scales, rhizome scales peltate, strongly dentate or ciliate, margin without notches
10'Hydathodes without persistent calcareous scales, rhizome scales pseudopeltate, entire to short-dentate margin with notches
11Lamina margin flat, translucent, with notches near apex only, rhizome with fully sclerified sheaths around the vascular strands
11'Lamina margin not differentiated or thickened, notches if present not only near apex, vascular strands without or with incompletely sclerified sheath
12Rhizome scales long-ciliate, lamina margin cartilaginous, strongly thickened, hydathodes with persistent calcareous scales
12'Rhizome scales entire to short-dentate, lamina margin not strongly thickened, hydathodes without persistent calcareous scales
13Fertile parts similar to sterile part, lamina 1.5-8 cm long, costa only distinct, lamina margin with notches
13'Fertile parts narrowed, lamina 12-52 cm long, veins distinct, lamina margin with-out notches or with notches sporadically present, absent from fertile fronds
14Sori in one row between adjacent veins, often forming transverse coenosori, deeply sunken
14'Sori in two rows between adjacent veins, not forming transverse coenosori, superficial
15Sori in two or more rows between midrib and margin between midrib and margin
15'Sori in one row between midrib and margin
16Sori in one row between adjacent veins, often forming transverse coenosori, rhizome scales with narrow, entire, subulate apex
16'Sori in two rows between adjacent veins, not forming transverse coenosori, rhizome scales not with subulate apex
17Rhizome scales 1.2-2.5 mm wide in the acumen, strongly dentate.
17'Rhizome scales with narrow, subulate, entire acumen
18Rhizome short, with phyllopods nearly contiguous, rhizome scales pseudopeltate.
18'Rhizome shortly elongated, phyllopods usually distinctly spaced, rhizome scales peltate
19Lamina margin without or with few notches, fronds monomorphic to weakly di-morphic
19'Lamina margin regularly with notches, fronds weakly to strongly dimorphic.
20Rhizome scales with narrow, subulate acumen, fronds gramineous, less than 2 mm wide
20'Rhizome scales with acumen not subulate, fronds usually not gramineous, over 2 mm wide
21Rhizome shortly elongated, phyllopods distinctly (0.5 cm) spaced, fronds quadrangular in cross section
21'Rhizome short, phyllopods contiguous, fronds not quadrangular in cross section.
22Sori deeply sunken
22'Sori superficial or slightly sunken
23Fertile parts similar to sterile part, margin without notches or notches sporadically present
23'Fertile parts narrowed, margin of fronds with notches regularly present.