Sect. Cyathea
Indusium an entire cup with even edge at maturity of sorus, if fragile sometimes breaking later
. . . . . . . . . . C. apoensis
Indusium otherwise or lacking
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 at maturity a disc with fairly even edge
. . . . . . . . . . C. negrosiana
Indusium at first covering sorus, apical parts very thin and caducous, an irregular disc remaining on old sorus
. . . . . . . . . . C. christii
Indusium otherwise or lacking
Indusium covering sorus to maturity, then breaking and persistent
Largest pinnules more than 100 x 20 mm; costules 5 mm. or more apart
. . . . . . . . . . C. acuminata
Largest pinnules not over 100 x 20 mm; costules 3-4.5 mm. apart
Costae and/or costules bearing bullate scales
Pinnules at base of larger pinnae distinctly stalked (stalks 2-4 mm.); costules 4-4.5 mm. apart
. . . . . . . . . . C. ferruginea
Pinnules sessile; costules usually not over 3.5 mm. apart
. . . . . . . . . . C. christii
Costae and costules lacking bullate scales
. . . . . . . . . . C. halconensis
Indusium hemitelioid (sometimes almost covering sorus to maturity, sometimes very small) or lacking
Pinna-rachis densely hairy throughout on lower surface
. . . . . . . . . . C. setulosa
Pinna-rachis hairy at most on distal part
Indusium entirely brown and rather firm, quite covering sorus to maturity, breaking only when old
Pinna-rachis densely covered with overlapping scales; indusium firm, shining
. . . . . . . . . . C. loheri
Pinna-rachis sparsely covered with very small pale fringed scales; indusium dull, thinner
. . . . . . . . . . C. cinerea
Indusium in part pale and fragile, breaking at maturity, or not entirely covering sorus
Pinnules 20-40 mm wide; costules 5-6 mm apart; lowest basiscopic vein from costa or base of costule
. . . . . . . . . . C. latipinnula
Pinnules rarely over 20 mm wide; costules not over 5 mm apart; basiscopic vein always from costule
Indusium visible as a scale backing the costule, not entirely hidden by sorus
Pinnules conspicuously stalked, stalks to 7 mm long
. . . . . . . . . . C. masapilidensis
Pinnules not conspicuously stalked
Indusium more than a semicircle, concave towards sorus and sometimes covering part of sorus to maturity
Pinna-rachis densely and persistently scaly
. . . . . . . . . . C. rufopannosa
Pinna-rachis not densely and persistently scaly
Indusium fragile, breaking and often in part disappearing
. . . . . . . . . . C. callosa
Indusium firm throughout
Pinnules about 100 mm long; segments of lamina mostly not constricted at base on acroscopic side; bullate or convex pale scales on costules
. . . . . . . . . . C. heterochlamydea
Pinnules about 60 mm long; segments of lamina mostly constricted at base on acroscopic side; no bullate scales
. . . . . . . . . . C. edanoi
Indusium not more than a semicircle, reflexed against costule at maturity
Bullate scales abundant and rather persistent on pinna-rachis (at least distally); pinna-rachis closely and finely warty after fall of scales
. . . . . . . . . . C. fuliginosa
Bullate scales lacking on pinna-rachis
Basal scales on costae bearing some marginal setae
. . . . . . . . . . C. caudata
Basal scales on costae without setae
. . . . . . . . . . C. fenicis
Indusium very small, hidden by sporangia
Scales on costae and costules all flat
. . . . . . . . . . C. microchlamys
Scales on costules bullate, some bullate scales often on costae
. . . . . . . . . . C. fenicis
Sect. Gymnosphaera
Reduced pinnae, their segments all with very narrow lamina, present at base of stipe, separated from normal pinnae
. . . . . . . . . . C. atropurpurea
Reduced basal pinnae, separate from the rest, lacking
. . . . . . . . . . C. lurida
Subsect. Sphaeropteris
Upper part of stipe and all rachises finely and closely warty
. . . . . . . . . . C. elmeri
Upper part of stipe and rachises conspicuously warty (warts not very fine and close)
Scattered pale bullate scales present on lower surface of costules
. . . . . . . . . . C. curranii
Bullate scales lacking on lower surface of costules
. . . . . . . . . . C. lepifera
Subsect. Fourniera
. . . . . . . . . . C. tripinnata
Subsect. Schizocaena
Fronds simply pinnate with deeply lobed pinnae, the largest sometimes with free pinnules at their base
. . . . . . . . . . C. binuangensis
Fronds amply bipinnate
Pinnules entire or with crenate edges
. . . . . . . . . . C. obliqua
Pinnules distinctly lobed
Sori indusiate
Pinnules of larger pinnae not lobed more than ¾ to costa throughout, no free basal pinnules, or sometimes one on lowest pinnule of lower pinnae
Bullate scales lacking on costules
. . . . . . . . . . C. integra
Bullate scales present on costules
Segments of pinnules acute, falcate; largest pinnules 20-30 mm wide
. . . . . . . . . . C. zamboangana
Segments of pinnules rounded; largest pinnules not over 20 mm wide
. . . . . . . . . . C. suluensis
Pinnules of larger pinnae always with one or more free basal segments
Copious long hairs on lower surface of veins as well as costules
. . . . . . . . . . C. robinsonii
No hairs on lower surface of veins
Free basal segments of largest pinnules deeply lobed; rachis and pinna-rachis densely persistently scaly; scales small, sub-bullate, setiferous
. . . . . . . . . . C. sibuyanensis
Free basal segments entire; rachises glabrescent
. . . . . . . . . . C. philippinensis
Sori without indusia
Long-spreading hairs abundant on lower surface of pinna-rachis and costae
. . . . . . . . . . C. trichophora
Long-spreading hairs lacking on lower surface of pinna-rachis
Largest pinnules with a free segment at the base; pinnules on stalks to 4 mm or more long
. . . . . . . . . . C. polypoda
Largest pinnules lacking a free segment at the base, almost sessile
. . . . . . . . . . C. squamulata
