We know T. longifolia and T. pauciflora are aggregates of described and undescribed taxa.

And we know that T. hatchii is a variable taxon - there are robust plants with yellow cilia, and slender plants with pink cilia.

Similarly T. pulchella is inconsistent, with T. caesia, T. pachyphylla, T. concinna and T. fimbriata so different they have been described as separate species by Petrie, Cheeseman and Colenso (two) respectively.

Similarly T. carnea is variable, with typical pink forms, and unusual yellow forms described as
T. imberbis by JD Hooker.

Similarly T. nervosa is a variable taxon, with differences in the postanther lobe and the petal spots that have led Scanlen to separate T. nervosa from T. decora.

Are we right in attributing this as simply within amphidiploid variation?
That is to ask, do these variations arise among plants of the same parentage?

Perhaps not. There is a range of parental possibilities within the T. longifolia and T. pauciflora aggregates (even more so for the latter if the original parents crossed in Australia, and seed from the subsequent amphidiploids migrated to New Zealand).

Perhaps a pink-flowered member of the T. longifolia agg. crossed with T. formosa to form the
precursor of the pink-ciliated T. hatchii and perhaps the yellow-ciliated form was fathered by
T. longifolia s.s.

Similarly which of the T. longifolia agg. is the parent of T. caesia? of T. fimbriata? of T. pachyphylla? of T. concinna? and of T. pulchella s.s? And which the parent of T. nervosa and T. decora?

Once the aggregates have been formally split (as Jeanes did with T. pauciflora agg. in Australia [3]), someone will have to redo these crosses artificially with the new taxa so we will then know which is the parent of which variation in what may be aggregates of similar but different crosses - otherwise we could never be sure the inconsistency is simply (as conventional wisdom has it) the variability to be expected from same-parent amphidiploids.