Asplenium chathamense#x2014; a new fern species from the Chatham Islands, New Zealand

摘要

Asplenium chathamensesp. nov. is a tetraploid species, closely related to bothA. flaccidumandA. terrestre, growing in scrub or on rock in coastal situations on the Chatham Islands of New Zealand. Its similarity toA. flaccidumsubsp.haurakiensesuggests that these two taxa may have evolved from coastal populations ofA. flaccidumsens. lat. which were formerly more widespread in New Zealand and perhaps like the morphologically variable plants seen today on the Kermadec Islands. It is postulated that octoploid plants ofA. terrestrearose by autopolyploidy from these tetraploid coastal populations and replaced them in areas other than those whereA. flaccidumsubsp. haurakiense andA. chathamensestill persist. The latter taxon is shown to have hybridised occasionally with other coastal species on the Chatham Islands.