Assessment Notes

Justification

Marthanella nidulosa is a gasteroid species known from three close sites in North America, recorded between 1981 and 1995. It is possible this species may have a small and restricted population, and therefore apply for a threatened category, but it may also be considerably under-recorded due to its hypogeous and inconspicuous nature. In addition, it has a large area of potentially appropriate habitat and range of putative hosts, so area of distribution and population size may be much larger. Thus it could fall into any cateogyr from Critically Endangered to Least Concern. Targeted search efforts and more research into habitat preference are needed, but at the moment the species is assessed as Data Deficient (DD).

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Taxonomic notes

This is the type species of the monotypic genus Marthanella, established based on morphological evidence (States and Fogel 1999).

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Geographic range

This species is only known from the United States of America (Coconino and Hila Counties in Arizona, USA) (States and Fogel 1999).

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Population and Trends

Marthanella nidulosa is only known from its description, from collections made between 1981 and 1995 in three close sites in Arizona. Since it is a small, hypogeous and therefore inconspicuous fungus, with several potential hosts, the number of unknown sites is expected to be higher. Nevertheless, since no putative host relationships have been confirmed and the known area of distribution is considerably small, it is difficult to estimate the population size without more records or search efforts. There is no evidence of population decline.

Population Trend: Unknown

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Habitat and Ecology

This is a hypogeous, gasteroid species, thought to be mycorrhizal. It has been found in mixed deciduous and conifer forests, so far under a combination of Quercus chrysolepis, Q. gambelli, Pinus ponderosa and P. edulis (States and Fogel 1999, UM Herbarium Data Group and IPT Admin L 2022).

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Threats

No major threats have been identified in the known distribution of the species. However, urbanisation, agricultural development, droughts, fire suppression and accumulation of fuel loads, and logging have been identified as threats for some of Mathanella nidulosa's putative hosts (Beckman 2016a; Farjon 2013a,b) and could present a threat to this species in other potential localities.

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Conservation Actions

Two known sites for this species are within the Coconino National Forest and thought to be protected. Targeted search efforts in areas of appropriate habitat and research into habitat and host preference for this species are needed to estimate the population size and potential distribution. Molecular studies to confirm placement of this species in a monotypic genus are also recommended.

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Source and Citation

Cunha, S.P. & Gonçalves, S.C. 2025. Marthanella nidulosa. The IUCN Red List of Threatened Species 2025: e.T265980031A266020915. Accessed on 23 November 2025.

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• Country occurrence