Echinodontium japonicum is a very rare wood inhabiting saprotrophic fungus associated with evergreen oaks (Quercus sessilifolia) of old growth forests in Japan. Despite having a conspicuous sporocarp, it has been recorded at two areas only and in total less than 10 times (1935, 1976 and four times after 2000). It is probably endemic to Japan. It has not been found in continental China, Taiwan or other place in Japan or elsewhere in east Asia despite intensive collections of wood-inhabiting fungi during the last 20 years. Old reports of E. japonicum from India (1977) are uncertain and not considered here.
The two Japanese localities in Nara and Miyazaki cover areas of ca. 2.5 km2 and 150 km2, respectively. Of four known localities in Miyazaki are, one has been is lost because of a dam construction. Old oak trees of Q. sessilifoliaare declining by the oak wilt disease in both of Nara and Miyazaki.
Echinodontium japonicum is assessed as Endangered (EN) based on the criteria B and C because the area of occupancy (AOO) is estimated to be less than 500 km2, the population is severely fragmented and from few localities, and potential habitat is declining, and the number of mature individuals is less than 250 and the population is undergoing continuing declining.
See Hattori and Ryvarden (1994) for morphological characters, and Tabata et al. (2000) for phylogenetic position.
Echinodontium japonicum is know from less than 10 records in Japan. Two records have been made from Kasuga-yama Hill (Nara Pref.), the type locality, in 1935 and 1976. Kasuga-yama covers an area of ca. 2.5 km2 and consists of an isolated natural evergreen oak forest, maintained because of a religious reason. In Miyazak, one collection was made in 1938, and five collections from four localities after 2000 (2003, 2004, 2006 and 2014). One of the latter sites has been lost because of a dam construction. Possible localities in Miyazaki in total cover an area of ca. 30 km2. Detailed records are as follows: Nara Pref., Kasuga-yama (1935, 1976; no further record). Miyazaki Pref., Suki (1938; no further record); Kobayashi 1 (2003; locality lost), Kobayashi 2 (2005); Kobayashi 3 (2006); Aya (2014). At each site, E. japonicum is known from a single host tree, only.
Population Trend: decreasing
Echinodontium japonicum is a wood-inhabiting fungus producing perennial basidiocarps on evergreen oaks in old growth forests. All of recent collections in Japan were made on Querqus sessilifolia, which prefers wet condition, and often seen along or near rivers and streams. This is an evergreen oak tree distributed in Japan and Taiwan, but sparse in many of the distribution areas. The sporocarps have been recorded on dead branches attached with living trees and/or trunks of Q. sessilifolia. As many most wood-inhabiting fungi, the mycelia in the wood is considered to live for many decades or longer, i.e. as long as appropriate wood conditions persist, i.e. until it is decomposed.
There are also old records of E. japonicum from India on Q. incana, Q. semicarpifolia and Q. dilatata which potentially may be correctly identified (Rattan 1977). However, there are also Indian records from Abies (Rattan 1977) and "conifer logs" which are more dubious because of improbable host trees (Rattan 1977, Prasher 2015).
Huge oak trees are declining in Japan due to the spread of the oak wilt disease caused by a bark beetle (Platypus quercivorus) and Raffaelea quercivora in the localities in Japan. One locality in Miyazaki was already lost by a dam construction. Quercus sessilifolia, the host tree species, is often distributed along streams and rivers, and further dam construction may be a potential serious threat for the fungus.
Most other possible habitats for this fungus have likely already been destroyed by deforestation in other areas of Japan.
Red Listed in Japan (2014) as CR+EN.