In the Rye and Hislop paper I cited as the source for this change, the two I. buxifolius varieties were collapsed into I. spathulatus. Since then, a paper has recently been published (see https://onlinelibrary.wiley.com/doi/10.1002/tax.13129) describing two new subspecies of I. spathulatus. Hence, I here swap the two buxifolius varieties into I. spathulatus subsp. spathulatus instead of into I. spathulatus