Hymenorchis serrulata is an endemic epiphyte orchid of New Caledonia known only from Dzumac, Haute Koéalagoguamba and Haute vallée de Bâ. H. serrulata occurs in humid forest on tree branches overhanging creeks (mostly on skinny bush, e.g. Metrosideros tree) at an altitudinal range 400-1050 m asl. Last observations fields on Dzumac station report sub-population ranging in size from 10 to 100 individuals before decline. Population size is not precisely known but is estimated to be nowadays fewer than 250 mature individuals with sub-populations fewer than 50 individuals. H. serrulata seems to be in decline on Dzumac station with the disappearance of the biggest part of the sub-population. The involved threats are unknown but the hypothesis of gathering by orchidophile seems realistic. Using criteria C, H.serrulata qualifies as Critically Endangered CR C2a(i).

Geographical area

H. serrulata is an endemic epiphyte orchid of New Caledonia known only from Dzumac, Haute Koéalagoguamba and Haute vallée de Bâ.

Population

Last observations fields on Dzumac station report sub-population ranging in size from 10 to 100 individuals before decline. Population size is not precisly known but is estimated to be nowadays fewer than 250 mature individuals with subpopulations fewer than 50 individuals.

Habitat

H. serrulata occurs in humid forest on tree branches overhanging creeks (mostly on skinny bushes, e.g. Metrosideros tree) at an altitudinal range 400-1050 m asl.

Threats

H. serrulata seems to be in decline on Dzumac station with the disappearance of the biggest part of the sub-population. The involved threats are unknown but the hypothesis of gathering by orchidophiles seems realistic. Due to its morphology (no pseudobulb), H. serrulata could be threatened by drought.

Conservation

H. serrulata is protected by legislation in Province Nord but does not occur in any protected areas. It is highly recommended to sensitize population in order to prevent any gathering, especially as trials on its propagation and transplatantion have systematically failed. It is also required to conduct field surveys on Houaïlou where H. serrulata has not been seen since 1981.

Bibliography

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.

Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.

Hallé N.; Aubréville A.; Leroy J. F.; 1977. Flore de la Nouvelle-Calédonie et dépendances. Volume 8: Orchidaceae.

Experts

Assessor(s): Butin, J., Laudereau, C., Amice, R., Cazé, H., Fleurot, D., Frayssinet, I., Garnier, D., Goxe, J., Gâteblé, G., Veillon, J., Villegente, J.

Reviewer(s): Tanguy, V.

Contributor(s): Faria, E.

Facilitator(s): Chanfreau, S.