Cyclophyllum merrillianum is a shrub, and can become a big tree, endemic to New Caledonia. It is found in the Grand Sud massif in the south of Grande Terre and on Lifou island in the Loyalty Islands. It occurs in littoral forests on ultramafic substrates at an altitude range of 20 to 67 m asl. This species is threatened by bushfires that contribute to the decline of its habitat quality. Its extend of occurrence (EOO) and area of occurrence (AOO) are estimated to be respectively 509 km² and 20 km² with a number of locations equal to three. Therefore, C. merrillianum is considered Endangered (EN) under criteria B1ab(iii,v)+2ab(iii,v), with continuing declines in the concerned sub-criteria.

Cyclophyllum merrillianum is endemic to New Caledonia where it is found in the Grand Sud massif in the south of Grande Terre and in Lifou island in the Loyalty Islands.

The population size is not known. Field observations indicate that the species is not common.

This species occurs in littoral forests on ultramafic substrates at an altitude range of 20 to 67 m asl.

This species is threatened by bushfires that contribute to the decline of its habitat quality.

Cyclophyllum merrillianum is not protected by legislation in New Caledonia and it does not occur in any protected area. It is recommended to inform the DSCGR (emergency services) on the presence of the species in the concerned areas. It is recommended to search areas surrounding the known subpopulations in order to better estimate its population size and threats.