Terrestrial ferns of small to large size, sometimes subaquatic on rocks beside streams. Rhizome short --to moderately long-creeping, sometimes suberect (never truly erect), radially symmetric, dictyostelic, bearing thin, brown scales with many superficial and marginal acicular hairs. Fronds short- to long-stipitate, the stipe with 2 vascular bundles at the base uniting upward into a single U-shaped vascular strand, lamina simple to mostly pinnate with +/- entire or crenate pinnae, the apical lamina pinna-like or widened and lobed basally merging with the upper pinnae, basal pinnae not reduced, pinnae crenate to entire, midribs of pinnae in pinnate species grooved above, but the grooves not confluent with rachis groove, unicellular, acicular hairs (sometimes hooked) present on both surfaces, capitate hairs and sessile glands sometimes present, surfaces usually pustular (when dry), veins in a pinnate group in each pinna-lobe or crenation (if present), almost all anastomosing to form an zig-zag excurrent vein terminating in the reduced sinus membrane, in deeply lobed pinnae the distal veinlets simple, free, terminating in the margin. Sori indusitate, sometimes exidusiate, often spreading along the veins (not excurrent vein), indusium often hairy, sometimes glandular as well; sporangia on a 2-seriate stalk, with acicular hairs (hooked hairs if those elsewhere are hooked) or sessile spherical glands (rarely both) either side of the annulus, the anulus longitudinal interrupted. Spores monolete, pale, with a continuous longitudinal wing and cross wings in most species, less often with many separate wings or papillae.
Subg. Pronephrium: veins in pinnae less than 10 pairs; or if more than 10 then sori indusiate; yellow spherical glands often present, at least on sporangi.
Sect. Pronephrium: hooked hairs absent from all parts of the plant; fronds not dimorphic; apical lamina pinna-like; sperical glands generally lacking, sometimes present on sporangia.
Sect. Dimorphopteris: hooked hairs absent from all parts of the plant; fronds mostly dimorphic (contracted fertile pinnae); apical lamina not pinna-like, +/- deltoid and deeply lboed at the base; spherical glands often present on adaxial surface of lamina and on sporangia.
Subg. Menisciopsis: veins in pinnae 10 pairs of more, or if fewer then excurrent veinlets all free; sori exindusiate; spherical glands never present.
Sect. Menisciopsis: hooked hairs absent from all parts of the plant; fronds not dimorphic; fronds not dimorphic; apical lamina pinna-like; spherical glands absent from all parts of the plant.
Sect. Gryptothrix: hooked hairs present on rhizome and usually elsewhere (lamina, sporangia etc.); fronds not dimorphic; apical lamina mostly pinna-like; spherical glands generally lacking from all parts of plants.
Key modified ex Holttum 1981, F1. Males. ser. 2, 1:509
Species in Papuasia
|1a.||Veins in pinnae less than 10 pairs, or if more than 10 then sori indusiate; yellow spherical glands often present, at least on sporangia||(subg. Pronephrium)
|Veins in pinnae 10 pairs or more, or if fewer then excurrent veinlets all free; sori exindusiate; spherical glands never present||(subg. Menisciopsis)
|2a.||Apical lamina pinna-like or much larger than pinnae; pinnae not auricled on acroscopic side; fronds of young plants simple (in P. beccarianum all fronds simple||(sect. Pronephrium)
|Apical lamina not pinna-like, or if so pinnae auricled on acroscopic base; fronds of young plants rarely simple||(sect. Dimorphopteris)
|3a.||No hooked hairs present on any part of the plant; sori rarely coalescent||(sect. Menisciopsis)
|Hooked hairs present on sporangia or on some other part of the plant; sori often elongate or coalescent||(sect. Gryptothrix)
|4a.||Pinnae of fronds of adult plants about equal in size to apical lamina||P. asperum|
|Apical lamina much larger than pinnae or fronds simple||5|
|5a.||No free pinnae, sometimes one small pair broadly adnate||P. beccarianum|
|Free pinnae present on adult plants||6|
|6a.||Sporangia bearing glands near annulus||P. womersleyi|
|Sporangia bearing setae, not glands near annulus||7|
|7a.||Apical segment lobed 1/3-1/4 towards midrib; pinnae to at least 1 cm long||8|
|Apical segment crenate; pinnae 1-5 mm long||P. micropinnatum|
|8a.||Pinnae 4-8 cm long||P. pentaphyllum|
|Pinnae not over 2 cm long||P. brauseanum|
|10a.||Pinnae not more than 3 cm long||11|
|Pinnae longer on mature plants||P. giluwense|
|11a.||Upper surface short appressed hairy; sori elongate||P. millarae|
|Upper surface glabrous; sori not elongate||P. peramelense|
|12a.||Fronds simple, 10-20 cm long with a cordate base||P. menisciicarpon|
|Fronds pinnate, or if siimple then smaller and sterile||13|
|13a.||Glands present on sporangia, in some cases setae also.||P celebicum|
|Sporangia lacking glands, setae present in most cses.||P. menisciicarpon|
[Note: Sphaerostephanos adenostegius (syn. Pronephrium nothofageti) may key out to couplet 13. It has stetate sporangia without glands and differs from both these species in that the lower surface of pinnae have scattered sessile glands between and/or on the veins.]
Species in Papuasia
|14a.||Pinnae 4-6 cm wide; edges distinctly serrate throughout||P. rubrinerve|
|Pinnae 2.5 - 3.5 cm wide; edges entire or nearly so||P. scopulorum|
|15a.||Caudex long-creeping with well-spaced fronds||P. triphyllum|
|Caudex short-creeping, fronds close together||16|
|16a.||Bud confined to base of uppermost pinna; pinnae widest in basal half; hydathodes on upper surface conspicuous||P. cuspidatum|
|Buds present at bases of several pinnae; pinnae usually widest above the middle; hydathodes not consipcuous||(P. ramosii)
|17a.||Hooked hairs present on sporangia||P. ramosii var. ramosii|
|Hooked hairs lacking on sporangia||P. ramosii var. nov. ex Solomons|