Acaulospora sporocarpia in the field.

Click on an image to see a larger version.

These three pictures were taken by Billy Stone.

This picture shows my GPS next to a sporocarp in situ. You can read the coordinates if you zoom in.
The field notes accompanying D.J. Stouffer's 1955 holotype collection of this species are minimal. The location is described as "approx. 70 km SW of Winslow (AZ), Barrowed Tank, in soil." That's pretty vague, and there's a whole lot of territory out there. Good luck finding that particular site; a pit, possibly a catchment pond for watering livestock, dug more than 50 years ago, out on the edge of the desert... somewhere...
In all the years before Stouffer's collection was made, in the 51 years between his and mine, or in the 5 years after as I update this, apparently nobody else has ever encountered this species, in Arizona, or anywhere (think about those words for a minute... nobody, ever, anywhere).

As near as I can tell, what that all means is that if one wanted to research this species, especially considering its resistance to pot-culturing thus far, this location, totaling only about ten acres in size, is the only verifiable spot on the entire planet where living specimens of this fungus, with mycorrhizal associations in place, can positively be said to be found. I must conclude that this bizarre little critter REALLY belongs on the Endangered Species List, and this location should be a protected habitat. Wouldn't you agree? If so, please call, write, or email Rob Larrañaga, with the U.S. Fish & Wildlife Service at the Las Vegas National Wildlife Refuge, and tell him you learned about this here and you think it needs protection. Thank you.

Here were two right next to each other.

These two were conjoined, like Siamese twins.

We had a pretty good crop of them.

Here's what they look like as they start to erode away.

We had significant snows during the early winter of 2006-2007 and, after some thawing in late January, I found this specimen (left) virtually unchanged from what it had looked like three months earlier. By mid-March, however, it was showing distinct signs of deterioration (center and right), becoming practically indistinguishable from the surrounding soil.
Of course, the next logical step is Sieving soil for spores!!!.

Aside from the obvious rarity of this organism, which I think should be enough to warrant some sort of protected status in and of itself (is there some part of 'only place on earth' that's ambiguous or difficult to understand?), part of why I ask that you contact FWS above is because the location where these collections were made is now under threat of development and I don't want to see it decimated. The opportunity to study A. sporocarpia in its habitat could be lost to science, and I think it needs some words spoken on its behalf.
I don't recommend it, but if you really want information on that whole awful mess, you can go here though, I assure you, that way madness lies...