C. radicatum was described in 1887 and its taxonomic placement has since been through phylogenetic analysis (Davoodian et al. 2021). As of the time the assessment only Pocillaria radicata and Diploderma radicatum have been listed as synonyms for this species in Species Fungorum (2023). However, May et al. (2003) also included Diploderma avellaneum as a heterotypic synonym, though it is still accepted as a separate species in Species Fungorum.

Castoreum radicatum was assessed instead of Diploderma avellaneum, one of the species in the EDGE assessments list, because they appear to be synonymous.

JUSTIFICATION: Castoreum radicatum is a hypogeous fungi native to Australia. Its distribution and estimated population size exceed thresholds for IUCN threatened categories and population decline is not expected to be significant given its host breadth and resistance to wildfires. Therefore, the species is assessed as Least Concern (LC).

C. radicatum is an Australian species, found mostly near the coast in the southeastern regions of New South Wales, Victoria, and Tasmania, but also from the Kangaroo Island of South Australia, the southern part of Western Australia and Queensland (Atlas of Living Australia, 2023).

This species is known from at least 41 sites (Atlas of Living Australia, 2023; GBIF.org, 2023). Search efforts are generally high in Australia and targeted plot sampling plot was done for hypogeous fungi within a 32 281 km2 study area in Victoria/New South Wales between 1996 and 2003 (Claridge et al. 2009), which led a a higher number of records for this region. Nevertheless, the total number of sites outside of this region is expected to be much higher given the low detectability of the fruitbodies. Population size is estimated at around 41000 individuals, following guidelines by Dahlberg and Mueller (2011) and assuming a 500 multiplier for unknown sites and 2 mature individuals per site.
Given its wide host breadth and resistance to fire, a significant population decline is not expected.

C. radicatum is a hypogeous ectomycorrhizal species, usually found with Eucalyptus and Acacia trees. It is not clear whether a fruiting is generally solitary or gregarious (some voucher labels indicate solitary fruiting others gregarious). Along with other species in its family, C. radicatum is thought to be fire-adapted, and able to survive wildfires and help the survival of mycophagous mammals post fire, who in turn help disperse its spores. However, fire may negatively impact this species though a decrease in litter depth, fallen trees and changes in tree stand density. This species was also shown to prefer areas with cooler mean annual temperatures and lower levels of precipitation. (Claridge et al. 2009) Jumpponen et al. (2004) also showed through association analysis that this species has a wide host breadth, including Acacia dealbata and different Eucalyptus species.

The decline in eucalyptus forests may present a threat to this species. Several Eucalyptus trees in Australia have been assessed as threatened by the IUCN List of Threatened Species mainly due to changes in land use for agriculture and urbanisation (Fensham et al., 2020). However, since C. radicatum has many potential Eucalyptus and Acacia spp. hosts, some of which have been assessed as Least Concern, it is difficult to determine the extent of these threats’ impact on this species.

C. radicatum was assessed as Least Concern by the Census of the Queensland Flora 2016 (Fechner, 2016). Moreover, around 22 out of the 41 known sites are within National Parks or Nature Reserves.

Unknown.