Assessment Notes

Justification

This species is assessed as Endangered under B1ab(iii,v)+B2ab(iii,v) due to its small geographic range, with an extent of occurrence calculated as 420 km² and area of occupancy calculated as 68 km², in combination with severe fragmentation and ongoing decline.

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Taxonomic notes

Macrocystidia reducta is a distinct secotioid species with a fishy odour. It is a member of a saprophytic mushroom family with few species globally and the family phylogenetically isolated within the order. The species is sequence barcoded.

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Geographic range

Macrocystidia reducta is a New Zealand endemic species which is only known from the Banks Peninsula in the South Island.

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Population and Trends

Macrocystidia reducta is restricted to the Banks Peninsula area of New Zealand where it occurs in a few remaining podocarp remnants. Pre european settlement Banks Peninsula was entirely forested but cleared for agriculture. This mushroom has been systematically surveyed in suitable habitats in the known area for 18 years. In addition many suitable habitats in other parts of New Zealand have been surveyed and the species not found. The species is perhaps the best surveyed uncommon species in New Zealand and the known sites represent the area of occurrence with a high degree of certainty. It is known from 18 sites. Each site is estimated to be represented by 20 mycelial genotypes corresponding to 200 mature individuals (Dahlberg and Mueller 2011). It is potentially present at up to 30 sites. Hence, the calculated size of the known population is 3600 mature individuals and the maximum size 6000 mature individuals.

The remaining Podocarp fragments are under threat from invasive weeds and animals from surrounding intensive farmland. The impact of farmland eutrophication is also a concern. The area of suitable habitat - "bare soil" - within these remnants is decreasing which is suspected to be causing a decline in the population of M. reducta.

Population Trend: decreasing

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Habitat and Ecology

Macrocystidia reducta is a saprotrophic soil-inhabiting secotoid (pouch) fungus growing on bare soil in Podocarp forest. It has limited ability to disperse spores and it is likely that animals (possibly extinct) play a critical role in dispersal.

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Threats

The habitat of the species in the known area has decreased substantially historically, and whilst some areas have some level of protection, many do not and the available habitat is likely to contract in the future and/or be impacted by adjacent land-use change and alien invasive species. The known sites are in areas with less than 10% of indigenous cover remaining and all in forest fragments surrounded by exotic grass pasture.

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Conservation Actions

The mode of dispersal needs investigation to ascertain if dispersal animals are still extant. Weed-control, pest management and fencing would be advantageous. More research is needed around the population structure.

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Use and Trade

The species is not utilized.

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Source and Citation

Cooper, J.A. 2019. Macrocystidia reducta. The IUCN Red List of Threatened Species 2019: e.T154285682A154287014. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T154285682A154287014.en .Accessed on 3 February 2024

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• Country occurrence