Key to the subspecies of P. synanthera

1 Stems 2.6(1.0–6.0) m long; rachises 74.1(48.0–91.0) cm long; pinnae7(4–12) per side of rachis; western Amazon region in Colombia, Peru, and Brazil at 146(90–250) m elevation ......................................................... subsp. robusta

- Stems 3.9(1.8–6.0) m long; rachises 92.2(55.0–124.0) cm long; pinnae12(7–18) per side of rachis; Cordilleras Central and Oriental in Colombia and eastern Andean slopes in Colombia, Ecuador, and Peru at 1064(400–1750) m elevation.................................................................................................................................................. subsp. synanthera