Barbeyella minutissima was first described in 1914 by Charles Meylan on the basis of a collection made at an altitude of 1,400 metres (4,600 ft) from the Swiss Jura in September the year before. Meylan thought the species warranted a new genus based on the unique mode of dehiscence and the makeup of the capillitium. The genus was named for the Swiss botanist William Barbey (1842–1914). It is monotypic species of genus Barbeyella.

Barbeyella minutissima is one of the smallest members of the Myxogastria and is considered rare, its habitat is restricted to rather narrow ecological niches. This species has been recorded from a limited number of localities, where it is often represented by collections of only a few sporocarps.
It has been assessed as VU A2a for Ukraine. However, in French Alps and in some regions of USA field collections of B. minutissima are stabile. But for most countries current trends are uncertain.
So during the workshop at Ekenäs in Feb 2015, its present preliminary status was found to be DD.

ASIA: India, Japan, Russia.
EUROPE: Finland, France, Germany,  Latvia, Lithuania, Poland, Romania, Russia, Sweden, Switzerland, Ukraine.
NORTH AMERICA: Mexico, USA (Washington, Oregon, California, North and South Carolina and Virginia).

15 country, 34 locality, 51 records; in 3 country current trends deteriorating, in 2 - stable, in others - uncertain
The sporangiophores of Barbeyella minutissima are developing from the semispherical protoplasmodium. In laboratory at room temperature, this process lasts roughly one day (Schnittler et al. 2000). Although the sporocarps is ephemeral, the plasmodium and myxamoebas could be surviving for long period. In field it is difficult to evaluate exactly generations for this species.
Active obsevation of potential substrates for B. minutissima in Ukrainian Carpathians during last 20 years didn’t bring positive result. Last collection   in this place was made by H. Krzemieniewska in September 1932. So for Ukraine Barbeyella minutissima is assessed as VU A2a.
The same situation could be posible for Finland and Poland. Often and stabile collections of B. minutissima are only in French Alps and in some regions of USA. For other countries current trends are uncertain.
In general the decline is difficult to evaluate and global status for this spesies is DD.

Its habitat corresponds to the mountainous spruce-fir forests of the Northern Hemisphere. It is largely restricted to altitudes between 500 and 2,500 metres (1,600 and 8,200 ft), occasionally appearing as low as sea level and as high as 3,500 metres (11,500 ft).
The species grows only on slightly to heavily rotten and barkless deadwood in coniferous forests in cool, moist areas. The wood is about 40 to 100% overgrown with Marchantiophyta, especially of the genera Nowellia or Cephalozia.
B. minutissima typically colonises slimy, algae-covered logs that have lost their bark and have been partially to completely covered by liverworts.
B. minutissima has been found growing on the liverwort Lepidozia reptans,  although Nowellia curvifolia is the main indicator for the slime mould. In addition to liverworts, Barbeyella is found socialised with monocellular algae. It is assumed that the protoplasmodium phagocytizes either the algae or the bacteria on their surface. Other Myxogastria species are often found together with Barbeyella, especially Lepidoderma tigrinum, Lamproderma columbinum and Colloderma oculatum. Aphanocladium album is a myxomyceticolous fungus (i.e., living on or within the fruit bodies of myxomycetes).
It is relatively common in fir forests on high-altitude Mexican volcanoes, suggesting that air-borne spore dispersal is effective.

Forestry and pollution-associated forest dieback in the natural zone of spruce-fir forests have contributed to a decline in available substrate associated with oldgrowth forest. All activities which further reduce dead wood should be considered a threat to maintaining populations of this species.

The habitat of this species is sensitive to change by human activities and intensively managed forests (without dead wood) do not provide suitable substrates. Conservation measures must be enacted to ensure sufficient amounts of dead wood are maintained to sustain populations of this species.

Because this species is very inconspicuous and difficult to find, targeted survyes should be undertaken of suitable microhabitats in order to form a more complete picture of the overall distribution of the species.
Global and Euro assessments currently difficult due to possibly very large number of unrecorded sites. It would be very useful to know the status of associated species such as Lepidozia reptans, Nowellia curvifolia. For example, Lepidozia, Nowellia is very common species. It would also be useful if we could define the microhabitat more precisely and assess its status. Guidelines for myxomycete generation time and other assessment parameters also require further development.

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