Kirchmair et al. (2004) recognized eight species in the mushroom genus Omphalotus: O. olearius (from southern Europe), O. illudens (from northern Europe and North America), O. subilludens (from the southeastern United States; Ammirati et al. 1985), O. olivascens (from the west coast of the United States and Mexico), O. mexicanus (from Middle America), O. nidiformis (from Australia), and O. japonicus (from Japan). Their molecular phylogenetic studies indicated two major clades within Omphalotus, the first consisting of O. illudens and O. mexicanus and the second including O. olearius, O. olivascens, O. japonicus, O. nidiformis, and O. subilludens. Although O. illudens and O. olearius have often been treated as synonyms, much evidence now indicates that both are valid species. In the analyses by Kirchmair et al., Omphalotus japonicus, a species formerly placed in the genus Lampteromyces based on its morphology, clustered as the sister group of O. olearius.
These mushrooms, especially O. illudens,are sometimes known as Jack O'Lanterns. This name derives from the orange color and the fact that the gills often glow eerily greenish (clearly visible under very dark conditions).
(Lincoff 1981; Arora 1986; Kirchmair et al. 2004 and references therein)
