The species is known from Japan (Honshu, Kyushu, Shikoku) and Taiwan.
This species is considered very rare but no detailed assessments of population size and possible decline exist. One out of six locations (17%) was destroyed by a typhoon in 1991, i.e. within the last generation. The extinction of the subpopulation in Fukuoka led to a 66% reduction in the extent of occurrence (EOO) and, if EOO were used as a proxy for population size assuming all sites are equal, this could represent a 66% population reduction. However, there are no additional data concerning declines prior to and after this event and there is uncertainty as to whether this loss represents an ongoing decline. This species has a generation length of 33 years and so declines for criterion A would need to be measured over a period of 100 years. As a result this species will not be assessed against criterion A and further work on population size and trend is recommended. Hurricanes are a continuing threat to this species and it should be noted that there will be no compensation for lost habitats through natural forest regeneration as this species is limited to old growth forests within protected areas.
Population Trend: decreasing
This species occurs in old-growth forests at the base of trunks of veteran trees of Cryptomeria japonica or Chamaecyparis obtusa in protected forests. Both tree hosts are Near Threatened according to IUCN Red List. It is an old-growth dependent species with an expected long generation time.
All known localities are within the borders of protected areas. It is likely that intensive forestry has led to a population decline in previous decades. Natural hazards such as typhoons are known and continuing threats.
All locations of the species are within the borders of protected areas. Detailed assessments of local subpopulations (size and trends) are needed and the geographic distribution should be clarified in underexplored regions.