Polytaenium

Kessler, Michael, Smith, Alan R. & Prado, Jefferson, 2017, Prodromus of a fern flora for Bolivia. XXVII. Pteridaceae, Phytotaxa 332 (3), pp. 201-250 : 241

Key to the Bolivian species of Polytaenium

1 Sporangia scattered between the veins, as well as on the veins, not in discrete linear sori; paraphyses lacking ......... P. citrifolium

– Sporangia restricted to the veins, the sori linear; paraphyses present .............................................................................................. 2

2 Sori in (2–)3–4(–8) parallel, deeply grooved lines .......................................................................................................... P. lineatum

– Sori oblique to the costae in irregular, superficial to slightly grooved lines .................................................................................... 3

3 Sori slightly sunken; blades oblanceolate, usually drying brownish green; costae abaxially strongly raised and angular, usually drying darker than the blades ......................................................................................................................................... P. cajenense

– Sori superficial; blades elliptic to oblanceolate, drying yellow-green to dark green; costae only slightly raised, rounded, drying paler than the blades or concolorous with them ............................................................................................................................... 4

4 Blades oblanceolate, the bases running to the rhizomes, usually drying dark green ................................................. P. brasilianum

– Blades elliptic, short-petiolate, drying yellow-green ................................................................................................. P. guayanense