Key to the morphologically similar species of P. zapalinamensis

1. Leaves 3-lobed, apices rounded to slightly acute...............................................................................................................................2

- Leaves 5-7 lobed, apices acute ...........................................................................................................................................................4

2. Petiolar nectaries opposite, stems green.............................................................................................................................................3

- Petiolar nectaries alternate, stems red ..................................................................................................................... P. zapalinamensis

3. Petiolar nectaries located in the lower third of the petiole ................................................................................................ P. hispidula

- Petiolar nectaries located in the middle of the petiole....................................................................................................... P. exsudans

4. Petiolar nectaries located near the base of the blade ..................................................................................................... P. bryonioides

- Petiolar nectaries located in the lower third of the petiole ................................................................................................ P. hispidula