Assessment Notes

Justification

Hygrophoropsis umbriceps is rarely recorded. Given that it is probably rare but under reported, it is estimated that there are no more than 7,500 mature individuals occurring in two subpopulations. Its habitat is declining in both quality and extent.  

The species is assessed as Near Threatened under criterion C as it meets the thresholds for Vulnerable regarding population size and continuing decline, but there is insufficient information to be able to state that the decline meets the thresholds for Vulnerable C1, whilst the population structure does not meet the requirements for Vulnerable C2a(i) or C2a(ii).

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Taxonomic notes

Hygrophoropsis umbriceps is an uncommon but rather easily recognised mushroom known from the North Island and upper South Island of New Zealand. Historically the name has been incorrectly used for another rather more common, but easily distinguished and undescribed mushroom. Care is required to interpret historical data.

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Geographic range

Hygrophoropsis umbriceps is an uncommonly recorded but rather easily recognised mushroom restricted to the North Island and upper South Island of New Zealand. It is only known from five confirmed records at five different localities.

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Population and Trends

The species is only known from five confirmed records in five sites in the northern half of New Zealand. The species is reasonably easily detected although it is likely to be under reported. The species has only been posted once among 25,000 curated iNaturalist postings from New Zealand. Thus, it is probably a rare or rarely fruiting species. Given that it is probably rare but under reported it is estimated that there are no more than 500 sites in total, each with five colonies representing three mature individuals, giving a total estimated population size of no more than 7,500 mature individuals occurring in two subpopulations.

Population Trend: decreasing

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Habitat and Ecology

Hygrophoropis umbriceps grows on soil in scrub with tea-tree (myrtaceaea). The species is probably ectomycorrhizal, but some species in the genus are known to be able to switch nutritional modes to saprotrophism. The habitat is widespread throughout much of New Zealand, but its extent is in decline due to land transformation and its quality is in decline due to invasive species coupled with nutrient runoff from adjacent intensive farming.

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Threats

The known sites are/were all relatively small patches of native bush surrounded by developed land. Of the five known sites the type locality in South Island has been cleared for pasture and one historic site in Auckland now developed for housing. Only one site is on protected land. These fragmented areas of indigenous bush are likely to continue to be under pressure from land-use change as land is cleared for changing farming practice and urban development. Invasive species are driving a decline in habitat quality as is nutrient run-off from adjacent large-scale agriculture.

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Conservation Actions

Research is needed regarding the identity of a mushroom from Tasmania known under the name Hygrophoropsis aurantiaca aff. This needs investigating to see if it represents the same species, and therefore a range extension.

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Use and Trade

The species is not utilized.

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Source and Citation

Cooper, J.A. 2019. Hygrophoropsis umbriceps. The IUCN Red List of Threatened Species 2019: e.T154276917A154278383. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T154276917A154278383.en .Accessed on 3 February 2024

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• Country occurrence