His conclusion is that the Lord Howe species, previously thought to be the same as Spiridens vieillardii from New Caledonia, is quite different and is in fact a species found nowhere else in the world. Its correct name is Spiridens muelleri, named after the famous botanist Ferdinand von Mueller. Lord Howe is the southernmost locality of any Spiridens species; the other seven species are entirely tropical. David's results were announced at the International Botanical Congress in Melbourne this year, and will be published in a scientific journal next year.
Thanks to David Meagher from the University of Melbourne for this information and his ongoing research.