Geranium microphyllum s.s. is endemic to the subantarctic islands. So the plant people all think is G. microphyllum in mainland New Zealand (incl. Stewart island) is an unnamed species complex (though distinction between these and G. potentilloides is not always easy). So on that basis ALL mainland New Zealand records of G. microphyllum are now referable to an unnamed complex of species, probably best called Geranium aff. microphyllum agg. (or G. potentilloides). NZPCN (or at least when I was on the committee 2003-2007) does not prepare fact sheets for unnamed entities. However, in most of the fact sheets I have done which have these types of issues I have noted these types of situations under the remarks/comments/cultural notes field.
Hope that helps.
Peter J. de Lange