[1][2] It is endemic to Australia's subtropical Lord Howe Island in the Tasman Sea.

[3] A global phylogeny of Asplenium published in 2020 divided the genus into eleven clades,[4] which were given informal names pending further taxonomic study.

A. surrogatum belongs to the "Neottopteris clade",[5] members of which generally have somewhat leathery leaf tissue.

It forms a clade with A. milnei and A. pteridoides, two other Lord Howe Island endemics, suggesting that all three species diverged after a single colonization of the island by their ancestor.

[6] This clade is sister to a large group of Pacific Ocean spleenworts.