Assessment Notes

Justification

Callistosporium vinosobrunneum is endemic to Hawai`i (US) where it was found in several places on the Big Island, and one on Kaua`i. It is restricted to Wet Montane Forests in which Metrosideros polymorpha (ʻŌhiʻa) is the dominant tree species. This tree is under immediate threat by ROD, Rapid ʻŌhiʻa Death, a fast spreading deadly disease caused by Ceratocystis fimbriata, so far only restricted to the Big Island of Hawaii. The spread of the pathogen is being monitored and in three years the pathogen had reached the sites where C. vinosobrunneum has been reported. Wet Montane Forest habitat is projected to decline at least 20% in the next 20 years, based on the spreading of the Ceratocystis wilt of Metrosideros polymorpha, the dominant tree in the habitat. A second threat is the widening of the Saddle Road on the Big Island; this project will destroy several of the kipukas, the tree islands surrounded by old lava streams, where this species was found.

The total number of mature individuals is estimated not to exceed 5,000, the amount of appropriate habitat has declined and is estimated to decline by an additional 20% in the next 20 years. It it is classified as VU (Vulnerable) under criterion C1.

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Taxonomic notes

Callistosporium vinosobrunneum is a distinctive, but small completely dark red-brown mushroom with white spores; it was described in 2011, though it had been detected much earlier (Desjardin and Hemmes 2011). It can be distinguished from the only other Callistosporium species occurring in the same habitats in Hawaii by the consistently dark red-brown fruitbodies.

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Geographic range

Callistosporium vinosobrunneum is endemic to Hawai`i and known from Big Island (several locations), and Kaua`i (one location).

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Population and Trends

Very rare, only known from a couple of sites on two small islands in the middle of the Pacific Ocean, in threatened habitats (because of tree death and human activities). The total number of sites, including undiscovered sites, is estimated to be less than 100, corresponding to an estimated number of genetically unique individuals of 500 and 5,000 mature individuals (cf. Dahlberg and Mueller 2011).

Population Trend: Decreasing

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Habitat and Ecology

Callistosporium vinosobrunneum is a saprotrophic fungus growing on rotten wood (Desjardin and Hemmes 2011). The species is restricted to Montane Wet Forests, which occur on four islands: Hawai`i, Kaua`i, Maui and Moloka`i at 1,200–2,200 m on windward aspects that receive rainfall exceeding 2,500 mm annually (Desjardin and Hemmes 2011), but the species is only known from two of those four islands.The habitat occurs in small patches (Desjardin and Hemmes 2011), surrounded by non-native vegetation types.

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Threats

All native Hawaiian vegetation types, including Montane Wet Forests, are under threat by invasion of alien species (Cuddihy and Stone 1990).  Montane Wet Forests are home to only 24 native Hawaiian fungi that depend on Metrosideros polymorpha (Desjardin and Hemmes 2011). Habitat destruction is the biggest threat to the occurrence of Callistosporium vinosobrunneum and the other species, first of all because of the rapidly spreading disease of the host tree (Metrosideros polymorpha; ʻŌhiʻa), caused by Ceratocystis fimbriata (Keith et al. 2015; College of Tropical Agricultural and Human Resources 2016). This fungus kills mature trees. Since it was first detected in the Kuna and Hilo Districts on the Big Island in Hawaii in 2013, it has spread rapidly, threatening all habitats in which Metrosideros is the dominant tree. The name of the disease, Rapid ʻŌhiʻa Death, is an indication of its sudden appearance and fast work. In the three years since its first detection it has spread up the volcanoes and has reached the habitats where C. vinosobrunneum occurs.  Wet Montane Forest habitat is projected to decline at least 20% in the next 20 years, based on the spreading of the Ceratocystis wilt of Metrosideros polymorpha, the dominant tree in the habitat. Secondly, habitat destruction of the kipukas, the tree islands in the middle of old lava flows, along the Saddle Road on the Big Island because of widening of the road has been a threat for years. The Saddle Road connects Hilo, Kona and Waimea with the observatory on Mauna Kea, and is the shortest route from Hilo to the Kona coast.

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Conservation Actions

Sanitary actions to restrict the spread of Ceratocystis fimbriata (the disease of the host tree Metrosideros polymorpha, ʻŌhiʻa) have to be taken immediately, and action to maintain the kipukas along the Saddle Road on the Big Island are needed. Cause of the infection, spread, identity, life cycle and ecology of Ceratocystis fimbriata have to be further researched. Ceratocystis-resistant strains of Metrosideros polymorpha have to be developed.

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Source and Citation

Vellinga, E.C. 2017. Callistosporium vinosobrunneum. The IUCN Red List of Threatened Species 2017: e.T95384402A95385414. Accessed on 23 November 2025.

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• Country occurrence