This species is only known from one site that has nearby mining encroachment that could potentially destroy it, causing this species to go go extinct or become critically endangered. Therefore, it qualifies under criterion D2.

The species is microscopic, requires specialized tools for recognition (isolation into pure culture then DNA sequencing or microscopy, or environmental sequencing), and was isolated in the Pakaraima Mountains, an area of potential habitat extending hundreds of km2.

Despite this, after hundreds of isolations in the region, this species has only been isolated once, and is also rare in metabarcoding sequence data from the area. Therefore, it is reasonable to believe that it may occur at few sites, or have an AOO <20km2, qualifying under criterion D2, even if one assumes it has many more sites where it occurs. Other species in this region have been shown to have

There are no synonyms. The species is monotypic, being the only described species in the genus Meredithblackwellia, but a 28S DNA sequence in GenBank (MH909035; Felix & Landell unpublished) suggests at least one other species occurs.

This species has only been isolated once, despite many years of collecting at the type locality both before and after isolation. It may also be an EDGE species, as it is monotypic.

The species is known from a single isolate from the Pakaraima Mountains of Guyana, 15 km east of Mount Ayanganna, at 710 M in elevation: 5°18′04.8″N, 59°54′40.4″W (Toome et al. 2012).

The nrITS sequence of the holotype has high pairwise similarity to two ITS1 sequences (99.46% over 185 bases and 98.92% over 184 bases, respectively) present in GlobalFungi from a metabarcoding study of topsoil in Jiangxi province, China (He et al. 2017). No other sequences with high pairwise similarity are present in GenBank, GlobalFungi, or UNITE (including HTS sequences). While these two sequences indicate this species, or a closely related species, could be present in China, this is not conclusive based on such a short barcode region or an assessment of the utility and variability of the ITS barcode in this species and genus. Therefore, this assessment only considers M. eburnea to occur in Guyana.

The population and current trends of M. eburnea are unknown, but it appears to be a rare species. In over 14 years of isolations from leaf surfaces in the area surrounding where the type was collected, resulting in 685 pure cultures (MC Aime, pers. comm.), M. eburnea was only isolated once, despite the fact that it grows well in culture (Toome et al. 2012). Additionally, in high-throughput sequencing reads of leaf litter, soil, and roots from the region where M. eburnea was found, only 26 out of 3.7 million reads (after processing for quality) were from M. eburnea (Stallman et al. 2024). This indicates some combination of rarity, low abundance, primer amplification bias, or general absence in these substrates.

Although presumably rare, the population is estimated to be > 10,000 mature individuals as this is a single-celled, microscopic yeast, in which each yeast cell could be considered a mature individual. In general, the population is deemed to be stable as the forest it has been collected is still relatively intact as primary, undisturbed rainforest.

The species has only been found on the phylloplane of a fern frond (species unknown) at 700m a.s.l. in Dicymbe corymbosa-dominated forests of the Pakaraima Mountains of Guyana.

More research is needed to determine if it may grow at different locations and on different substrates. It is presumably saprotrophic.

In general, large areas of primary, undisturbed similar habitat to the area where M. eburnea was collected are still relatively intact, but encroaching mining activity, within 5 kilometers, threatens the only location this species has been collected. Artisanal and small-scale mining is the leading cause of deforestation in Guyana (Guyana Forestry Commission 2019).

No conservation actions are currently in place. As the species is only known from one site, protecting this site from destruction for mining would be the most urgent conservation action.

Additional searches for this species at or around the type locality, or in similar habitats in Guyana may provide more information on its distribution and the number of populations. Phylloplane isolations from ferns and soil isolations in Jiangxi province, China at or around sample GF05011674S from He et al. (2017), where nrITS1 sequences share high pairwise similarity with M. eburnea, could help determine whether M. eburnea or a related species occurs there.

n/a