are inamyloid, so they do not adsorb iodine when stained with Melzer's reagent. The paraphyses are club-shaped, and have a pale brown color, with tips that are up to 10 µm thick. Although the edibility of the fruit bodies is often listed as "unknown", consumption of this fungus is not recommended as similar species in the family Helvellaceae contain varying levels of MMH. MMH can be removed by boiling in a well ventilated area but consumption of any MMH-producing mushroom is not advisable (see article on G. Esculenta). Roger Phillips lists the species as poisonous. Similar species Helvella queletii has a roughly similar form and appearance, but the ribbing in that species does not extend up the margin as does H. acetabulum. H. griseoalba has ribs that extend halfway up the sides of the fruit body, but the color of the cup is pale to dark gray rather than cream. The fruit bodies also resemble those of H. costifera, but the latter species is distinguished by its grayish to grayish-brown hymenium; like H. acetabulum, it has ribs that extend to most of the outside of the fruit body. There are sometimes intermediate forms between the two species, making them difficult to distinguish. H. robusta is also similar to H. acetabulum, but has a lighter-colored hymenium, a robust stem, and the margin of the fruit body is often bent over the stem at maturity. In contrast, H. acetabulum never has the edge of the fruit body bent over the stem, and the stem is "indistinct or prominent, but never robust". Another similar species is H. leucomelaena. Distribution and habitat This fungus is widespread in North America and Europe. In North America, the distribution extends north to Alberta, Canada. In Mexico, it has been collected from State of Mexico, Guanajuato, Guerrero, and Tlaxcala. It is also found in Israel, Jordan, Turkey, Iran China (Xinjiang) and Japan. The fruit bodies grows solitary, scattered, or clustered together on soil in both coniferous and deciduous woods, typically in spring and summer. A preference for growing in association with coast live oak (Quercus agrifolia) has been noted for Californian populations. References acetabulum Fungi described in 1753 Fungi of North America Fungi of Europe Fungi of Asia Inedible fungi Taxa named by Carl Linnaeus