As circumscribed by Sutherland et al. (2011), the genus Pyropia encompasses species
displaying a wide range of morphological forms, a wide colour spectrum and at
least four different types of arrangements of reproductive regions on sexual thalli. This genus is the most speciose of the Bangiales, and it also has the widest geographic
distribution, with species occurring from tropical to cold temperate waters. Pyropia
plicata has been recognised in the flora of mainland New Zealand for a long time,
but has remained without a formal name as a result of confusion over the application
of the name P. columbina. This situation was able to be clarified only after material
collected in the subantarctic islands became available for study (Nelson and Broom
2010). Although mature thalli of Pyropia plicata range widely in size and also in colour,
the fundamental shape of the blade, and the arrangement of reproductive regions
are consistent, and enable this species to be readily distinguished. Within the genus
Pyropia, P. plicata is grouped within a clade of at least 15 southern hemisphere species.
The majority of these species are currently undescribed but the clade includes P. virididentata,
P. cinnomomea and P. columbina (Broom et al. 2010, Sutherland et al. 2011).