Sect. Cyathea
Pinnules not over 30 mm. long; segments mostly constricted at base or the lower ones quite free
. . . . . . . . . . C. perpelvigera
Pinnules longer, or if under 30 mm. long without free basal segments
Indusium at maturity an almost flat disc, symmetric or not, in some cases hidden by mature sorus, in some cases the residual part of a complete indusium of which the thin apical part falls away at maturity
Indusium a very narrow ring around base of receptacle
Lower surface of pinna-rachis and costae bearing flexuous pale hairs and scattered irregular small pale scales with long flexuous slender marginal hairs
. . . . . . . . . . C. batjanensis
Lower surface of pinna-rachis bearing small scales with short fringe of hairs
. . . . . . . . . . C. ternatea
Indusium ultimately a regular or irregular disc, almost or quite as big as base of sorus, if irregular, usually the base of a formerly complete indusium
. . . . . . . . . . C. albidosquamata
Indusium otherwise or lacking
Indusium covering sorus to maturity, then breaking and persistent
. . . . . . . . . . C. inquinans
Indusium a very small dark scale on costular side of receptacle
. . . . . . . . . . C. amboinensis
Sect. Gymnosphaera
Reduced pinnae present at base of stipe, separated from normal pinnae
. . . . . . . . . . C. annae
Reduced pinnae, separate from the rest, lacking; lower pinnae in some cases reduced gradually almost to base of stipe
Sterile fronds simply pinnate with entire pinnae, the true frond-apex short and abortive, evident above attachment of uppermost pinna
. . . . . . . . . . C. biformis
Fronds with normal apex
. . . . . . . . . . C. acrostichoides
Subsect. Sphaeropteris
Upper part of stipe and all rachises finely and very closely warty
. . . . . . . . . . C. sangirensis
Upper part of stipe and rachises thorny (or conspicuously warty, warts not very fine and close)
Bullate scales present on lower surface of costae and costules
. . . . . . . . . . C. pilulifera
Bullate scales lacking on lower surface of costae and costules
. . . . . . . . . . C. angiensis
Subsect. Fourniera
Veins and lower surface of lamina bearing finely fringed interlacing scales which cover lower surface of leaflets
. . . . . . . . . . C. celebica
Scales absent from lower surface of veins
. . . . . . . . . . C. tripinnata
Subsect. Schizocaena
Fronds simply pinnate, pinnae entire
. . . . . . . . . . C. moluccana
Fronds bipinnate
. . . . . . . . . . C. suluensis
Subsect. Sarcopholis
Pinna-rachis hairy on the lower surface
. . . . . . . . . . C. setifera
Pinna-rachis not hairy on lower surface
. . . . . . . . . . C. tripinnatifida
