Te Papa’s biodiversity scientists regularly describe new species of plants and animals. Just added to this list is another New Zealand fern.
This new species is a Hymenophyllum filmy fern. Hymenophyllum means thin-leaved. The fronds of most species are only one cell thick, giving them a translucent appearance.
We have named the new species Hymenophyllum pluviatile. The second (or specific) part of its name is Latin for “of rain or pertaining to rain”. This alludes to its occurrence in areas of high rainfall. It has scattered populations along New Zealand’s west coast, from Northland to Fiordland, with an outlying record from Taupo. A recent independent conservation assessment ranked it as Threatened (Nationally Vulnerable).
The description of Hymenophyllum pluviatile was a collaborative project involving scientists from Te Papa, The University of Melbourne, and New Zealand’s Department of Conservation.
The first suggestion that it might be a distinct species was actually made several decades ago. We were prompted into action when we recently sequenced its DNA and discovered it was quite different from its relatives.
Another outcome of this project was that we realised that New Zealand’s Hymenophyllum atrovirens was actually the same as Australia’s Hymenophyllum australe. This means that where we previously had Hymenophyllum atrovirens confined to New Zealand and Hymenophyllum australe confined to Australia, we actually have Hymenophyllum australe in both Australia and New Zealand.
Hymenophyllum pluviatile is usually easily distinguished from H. australe; in New Zealand, the latter grows in or around streams, whereas Hymenophyllum pluviatile grows on trees, rocks, and sometimes on the ground.
Hymenophyllum pluviatile is more likely to be confused with the much more common H. flexuosum. They grow in similar habitats, but H. flexuosum is generally bigger and more robust, usually has a more flexuous (i.e., wavy) frond, and has a wider wing on its stipe (i.e., frond stalk).
Abstract of the scientific paper describing Hymenophyllum pluviatile and synonymising Hymenophyllum atrovirens with Hymenophyllum australe. The paper contains a distribution map, more images, and more details about how to distinguish the species.
We have newly-described several other New Zealand ferns recently:
And there are still more additions on the way…