Myoporum rapense is a shrub or tree species native to Aotearoa / New Zealand (Kermadec Islands) and French Polynesia. In New Zealand the species is considered widespread, being a common species on the Kermadec Islands and on Macauley Island it is the dominant shrub / tree. The species is secure on most of the larger Kermadec Islands, all of which are a nature reserve. If the species range remains predator free this species is unlikely to be threatened, with the only major risk being volcanic eruptions on Raoul Island. The total population is estimated as more than 65,000 mature individuals. It is assessed as Least Concern.

This species occurs in Aotearoa / New Zealand on the Kermadec Islands and French Polynesia on the islands of Rapa and Tubuai. Distribution map is generalised.

There is no accurate population estimate for this species, but the population is thought to be declining. However, the species is widespread and abundant in coastal forest and shrubland on all the larger islands and islets of the Northern Kermadec Islands group. There a collective population of >50,000 mature individuals is estimated. On the Southern Kermadec Islands group it is only known from Macauley and Hazard Islands. It is naturally scarce on Hazard (a small windswept sparingly vegetated island) but locally common and recovering on Macauley Island where 5,000–10,000 trees are estimated to grow along the eastern cliff faces of the seaward Macauley Crater, and as the result of the eradication of Polynesian Rat/kiore (Rattus exulans) Myoporum was noted spreading across the Macauley plateau (de Lange 2015). The species also occurs on at least two islands in French Polynesia but estimates of subpopulations there are not known.

The subspecies on the Kermadec Islands, Myoporum rapense subsp. kermadecense, is a common tree and shrub of coastal shrubland and forest (Sykes 1987 as Myoporum kermadecense) that along with Coprosma petiolata forms a distinct association at the back of cobble and boulder beaches and on exposed cliff faces of Raoul Island. In suitable sites it may extend well inland to colonise open rubble slopes, cliff faces and slip scars. In the coastal portion of that island, it also co-associates with Metrosideros kermadecensis. On the Meyers and Herald Islets it may form the dominant shrub / tree vegetation (such as on the Chanters), growing on the margins of the Metrosideros forest that dominants the better developed soils and slopes of the taller more vegetated islands. On Macauley Island it is the dominant shrub / tree, forming the sole woody cover over portions of the seaward Macauley Crater (de Lange 2015). On Hazard Island it is only known from a few shrubs growing on the margins of the island’s windswept summit slope.

There is no evidence that the subspecies Myoporum rapense subsp. kermadecense has undergone any major historical range contraction on the Northern Kermadec Islands group. Historical records suggest that it may have been nearly extirpated from Macauley Island (de Lange 2015) because of feral goat (Capra hircus) browsing pressure – which was extreme on that island, reducing it to a ‘lawn’ like grassland of Ehrharta stipoides by the late 1960's (Sykes 1977). By that stage Myoporum was known only from specimens growing on inaccessible cliff and talus slopes. Following goat eradication in 1970 Myoporum expanded its range but was not detected on the Macauley Plateau until May 2011. This range expansion is assumed to have happened because of the 2006 Polynesian Rat/kiore eradication (de Lange 2015), it seems that this species consumed Myoporum fruits and seeds, so limiting range expansion.

Provided the Kermadec Islands remain predator free Myoporum rapense subsp. kermadecense is unlikely to be threatened. The only major risk to the species is volcanic eruptions on Raoul Island, which is its stronghold, and, though less likely an eruption on Macauley Island. These are risks which presumably it has evolved with as the Kermadec Islands are notoriously volcanically active (Gentry 2013).

Forests on Rapa Island in French Polynesia, where the species is known to occur, has been heavily degraded due to overgrazing by cattle and goats (Butaud et al. 2014).

This species is occasionally cultivated in Aotearoa / New Zealand.

The main risk to Myoporum rapense subsp. kermadecense and indeed all the Kermadec Islands biota is the potential for new incursions of pest species – as such it is imperative that biosecurity measures currently in place are maintained. During the sars-cov-2 outbreak the resident rangers on Raoul Island were moved back to Aotearoa / New Zealand (2020) and since that time there has not been a continuous human presence on the islands. This is a risk as the islands are frequently visited by boats / ships and illegal landings could be a source of new diseases / pest incursions. The risk is greater for the Southern Kermadec Islands, as these have never had short or long-term human occupation, and are remote from main shipping routes, thus detecting incursions in a timely manner is less likely. To safeguard the island group, it is important that the islands are visited more frequently by those versed in biosecurity, particularly animal and plant pest detection.

New Zealand Threat Classification System assessed this species as ‘At Risk / Declining’ Qualified ‘CD’ [Conservation Dependent], ‘IE’ [Island Endemic] (de Lange et al. 2018).