A New Species of Pittosporum Described from the Poor Knights Islands, Northland, Aotearoa/New Zealand

Abstract

Here we describe Pittosporum roimata, the only vascular plant endemic to the Poor Knights Islands, Northland, Aotearoa/New Zealand. This new species has previously been referred to as a distinct yellow-flowered variant of Pittosporum cornifolium (tāwhiri karo, wharewhareatua), a morphologically similar epiphytic shrub known from both main islands of New Zealand as well as other offshore islands. We have segregated this new species from P. cornifolium based on morphology, DNA sequence variation, as well as distribution. Pittosporum roimata is distinguished from P. cornifolium by flowers with yellow petals, larger inflorescences, and producing several terminal fruits per stem. Herbarium specimens of P. roimata statistically have larger leaves and shorter petioles than specimens of P. cornifolium. Pittosporum roimata is locally common on the islands of Tawhiti Rahi, Aorangi, and Aorangaia, growing on rocky substrates associated with Xeronema callistemon (raupo taranga) and Metrosideros excelsa (pōhutukawa). Using the current New Zealand Threat Classification System, we suggest a preliminary classification of this new species as ‘at risk/naturally uncommon’ qualified data poor [DP], one location [OL].