Taxonomy
Synonyms
Athyrium australe var. gemmiferum C.Chr. • Athyrium rosenstockii Copel.Red List Status -
Endangered (EN) , assessed in 28/05/2018
Diplazium rosenstockii is an endemic terrestrial fern from New Caledonia's Loyalty Islands, where it occurs on Lifou and Maré. It is found in wet and shady dolines on both islands. Its subpopulations are in good shape, albeit very small, and their habitat is threatened in the vicinity of the dolines (land clearing for crops, tourism). Its area of occupancy (AOO) and extent of occurrence (EOO) are 20 and 898 km², respectively, and the numer of locations is 5. Therefore, D. rosenstockii is listed as Endangered under criteria B1ab(iii)+2ab(iii).
Geographical area
D. rosenstockii is endemic to New Caledonia's Loyalty Islands. It was historically known from Maré, but has also recently been discovered on Lifou (Butaud 2014).
Population
Subpopulations are very small but usually in good shape, and regeneration has been observed (Butaud 2014). Total population size is unknown.
Habitat
This fern is known from a few wet and shady dolines on calcareous rocks on Lifou and Maré islands. It probably occurs in most such habitats on both islands (Butaud 2014).
Threats
The main threat to this species is habitat degradation in the vicinity of the dolines. This can be due to land clearing for crops when the dolines are close to human settlements. Tourism, though scarce, can also be a disturbance.
Conservation
Unprotected by legislation in New Caledonia, this species does not occur in any protected areas. The Loyalty Islands' dolines it grows in are a very rare and fragile habitat, which needs to be protected from clearing and tourism. Further prospection in those areas is recommended to better estimate its popuation and conservation status.
Bibliography
Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.
Brownlie G. 1969. Flore de la Nouvelle-Calédonie et Dépendances, Volume 03 : Pteridophytae.
Morat, P.; Jaffré, T.; Tronchet, F.; Munzinger, J.; Pillon, Y.; Veillon, J.-M. and Chalopin, M. 2012. Le référentiel taxonomique Florical et les caractéristiques de la flore vasculaire indigène de la Nouvelle-Calédonie [The taxonomic database « FLORICAL » and characteristics of the indigenous flora of New Caledonia]. Adansonia sér 3(34) , p.177-219.
Butaud, J.-F. 2014. Flore des îles Loyauté (Nouvelle-Calédonie) : plantes patrimoniales, plantes envahissantes et espaces naturels remarquables.
Experts
Assessor(s): Amice, R., Bruy, D., Butin, J., Cazé, H., Dumontet, V., Fleurot, D., Gâteblé, G., Haverkamp, C., Héquet, V., Lagrange, A., Laudereau, C., Tiavouane, J., Tron, F., Veillon, J.
Reviewer(s): Lannuzel, G.
Facilitator(s): Meyer, S., Warimavute, G., Butaud, J.