Abstract
Asplenium lepidotum is described as a new and uncommon fern endemic to the northwest of the South Island of New Zealand. It is related to Asplenium oblongifolium and Asplenium obtusatum , and like them, A. lepidotum has pinnate fronds and is probably tetraploid, the latter character state being inferred for A. lepidotum from its spore size. Asplenium lepidotum is distinguished by abundant scales on the adaxial surface of its pinnae, separating it from both A. oblongifolium and A. obtusatum , as well as Asplenium northlandicum , which is similarly pinnate but octoploid. Furthermore, A. lepidotum has broader scales than A. oblongifolium , and is primarily rupestral at base‐rich, inland sites compared with the coastal A. obtusatum and A. northlandicum . Asplenium lepidotum is usually easily distinguished from the octoploid Asplenium lyallii , particularly when the latter is bipinnate or lacking scales on the adaxial surface of its pinnae. From pinnate plants of A. lyallii with abundant scales on the adaxial surface of their pinnae, A. lepidotum can be separated by its smaller spores and less divided terminal pinna. We suggest that A. lepidotum be given a conservation ranking of Naturally Uncommon, with Range Restricted and Data Poor qualifiers.