Meiorganum neocaledonicum is a wood inhabiting fungus that is likely to be very long lived with a generation length of perhaps 100 years or more. The generation length of its host is estimated at 80 years. There are three severely fragmented populations in South Pacific: New Caledonia, North Queensland and Papua New Guinea. The fungus is associated with two or possibly more Kauri (Agathis) species.
Using Dahlberg & Mueller’s multiplier for wood inhabiting fungi and the observations made in the last 100 years we would estimate the population of mature individuals to be < 50 worldwide.
Allowing for as yet undiscovered localities is difficult since we do not know whether the fungus is an Agathis specialist or whether it is associated with specific species of Agathis. There are probably some individuals in as yet un-surveyed sites, so we would tentatively estimate there to be 4 sites in New Caledonia, three in PNG and 2 in North Queensland.
The current distribution of this taxon is concentrated in forest remnants which contain Agathis. The host has been severely reduce in numbers and extent over the past two centuries and the remaining fragmented populations are now threatened by both fire and disease. Three of the 18 species of Agathis are red listed. Recent events in New Zealand have highlighted just how vulnerable the host can be to introduced diseases. Climate change has already shown that there is an increased risk of fire in both Queensland and New Caledonia, even in protected areas and although the resilience of this species to these events is not known, its host is vulnerable.
On this basis we have concluded that Meiorganum neocaledonicum should be classed as ‘critically endangered’.

Fruiting body:  a bracket, semicircular, spathulate; fleshy spongy; 80 – 150 mm diameter; glabrous; viscid when wet; dirty pale golden.
Hymenium formed as a layer of pores on the lower surface 1 – 2 mm in depth; pores firm, irregular, laberinthine; becoming more or less dentate in older specimens; tubes six sided.
Smell: fragrant, distinctive , pleasant.
Flesh: red brown with the red component being soluble in alcohol.
Spore print; grey brown with a lilac purple component.
Spores: ovoid ellipsoid; 3.2 – 4 × 2.5 – 3 µm; smooth.
Basidia: narrowly clavate, 25 – 45 µm long.
Cystidia: fusiform; 20 – 45 × 6 – 12 µm.
Substrate: on dead and dying wood of kauri trees. Agathis lanceolata in New Caledonia,  Agathis robusta in Queensland and Agathis sp in PNG.

This is an unusual polypore that is only found growing on Kauri trees and appears to fruit when the trees are mature and dead or dying. Agathis is an ancient genus of trees, long exploited for its fine timber and the resin it produces. Over the last three centuries both the number of Kauri trees and the extent of the forests in which they occur, have reduced dramatically.
The fungus was first described by Roger Heim in 1966 from material collected in New Caledonia in 1964 and 1965. Subsequently there have been five collections, one in PNG in 1995, one in Queensland in 2009 and three in New Caledonia in 2015, 2016 and 2018.

There are so few records of this fungus that it is impossible to detect any trends. Two records (both duplicated) appear in the GBIF database together with a record from Montpellier, attributed to West Africa (Sierra Leone) but thought to be based on material collected from New Caledonia (No collection details are recorded). The Queensland material consists of a single record from 2009, the PNG material consists of a single record from 1995. In New Caledonia there are Heim’s three original collections from 1964 and 1965, and three recent records post 2010.

Meiorganum neocaledonicum is a wood inhabiting fungus that is likely to be very long lived with a generation length of perhaps 100 years or more. The generation length of its host is estimated at 80 years. There are three severely fragmented populations in South Pacific: New Caledonia, North Queensland and Papua New Guinea. The fungus is associated with two or possibly more Kauri (Agathis) species.

The host of Meiorganum neocaledonicum is the ancient coniferous genus Agathis which is restricted to the sub-tropical forests of the south western pacific. Notably the islands of Borneo, Papua New Guinea, Northern New Zealand, New Caledonia and the coasts of Queensland in Australia. Everywhere Kauri trees occur they have been harvested for their timber and the majority of the once huge Kauri forests have gone (Whitmore 1980). Forest clearing is still proceeding in all the states in which this fungus has been found. Worldwide it is estimated that less than 5% of the original Kauri forests remain. Climate change is increasing the risk of fire to which the fungus and its host are vulnerable. Recent experience in New Zealand with Kauri dieback suggests that Agathis may also be vulnerable to disease. Agathis lanceolata the host in New Caledonia is IUCN listed as Vulnerable.

Neither the fungus nor its host (?) are protected at any of their present locations.

The biology and host specificity of this species both need clarification. Better recording of host preference is needed. Curation of collections is so far only achieved in Australia there being no fungal herbaria in PNG or New Caledonia.

Atlas de la Nouvelle Caledonie (1983). Auteur?  Imprimerie H. Dridé
Atlas of Living Australia 2019: ala.org.au
de Laubenfels, David J. 1988. Coniferales.P. 337–453 in Flora Malesiana, Series I, Vol. 10. Dordrecht: Kluwer Academic.
Enright N.J. and D. Goldblum (1998).Stand Structure of the Emergent Conifer Agathisovata in Forest and Maquis, ProvinceSud, New Caledonia. Journal of Biogeography, Vol. 25, No. 4, pp. 641-648
Geospatial Conservation Assessment Tool: geocat.kew.org
Global Biodiversity Information Facility: gbif.org
Heim, R. 1966.Revue Mycol., 31(2), 157.

Thomas, P. 2010. Agathis lanceolata.The IUCN Red List of Threatened Species 2010.
Whitmore T.C. & Page C.N. (1980). Evolutionary implications of the distribution and ecology of the tropical conifer Agathis. New Phytol 84: 407-416.