Re-evaluation of the taxonomic status of Christella dentata (Thelypteridaceae) supports recognition of one species in New Zealand: Tuhinga 27

Tuhinga 27: 50-55

ABSTRACT: Several publications over the last 30 years have suggested that there may be more than one species of Christella in New Zealand: one with creeping rhizomes found in Northland and the Kermadec Islands, referable to the widespread species C. dentata; and another of uncertain status with short-creeping or erect rhizomes, confined to thermal regions in the North Island and the Kermadec Islands. The taxonomic status of these plants has been re-evaluated based on collections in the main New Zealand herbaria and field observations from botanists who have collected them. Analysis of frond and rhizome morphology, spore size and cytology indicates that the only difference between the two groups is the nature of the rhizome. Based on current knowledge, we conclude that only one rather variable species, C. dentata, is indigenous to New Zealand, and that it shows similar variation to the species in Australia. In addition, there are a few populations naturalised in northern New Zealand, some of which are slightly different in appearance to the indigenous plants and have probably been introduced from overseas sources, and others that may have originated from indigenous plants brought into cultivation.

KEYWORDS: Christella dentata, Thelypteridaceae, New Zealand flora, taxonomy.