Omphalotus olivascens

{{Speciesbox

| image = Omphalotus olivascens 125218.jpg

| genus = Omphalotus

| species = olivascens

| authority = H.E.Bigelow, O.K.Mill. & Thiers (1976)

}}

{{mycomorphbox

| name = Omphalotus olivascens

| whichGills = decurrent

| capShape = infundibuliform

| hymeniumType = gills

| stipeCharacter = bare

| ecologicalType = saprotrophic

| sporePrintColor = yellow

| howEdible = poisonous

}}

Omphalotus olivascens, commonly known as the western jack-o'-lantern mushroom, is an orange to brown-colored gilled poisonous mushroom endemic to the California Floristic Province. It is sometimes mistaken for chanterelles.

Taxonomy

The fungus was described as new to science in 1976 by American mycologists Howard E. Bigelow, Orson K. Miller Jr., and Harry D. Thiers. A subspecies with blue flesh, O. olivascens var. indigo, was described growing on live oak in Baja California, Mexico.

Description

The cap is {{Cvt|4-18|cm}} wide. The stalks are {{Cvt|4-15|cm}} long and {{Cvt|1-4|cm}} wide. The spores are white to pale yellow.{{Cite book |last1=Davis |first1=R. Michael |url=https://www.worldcat.org/oclc/797915861 |title=Field Guide to Mushrooms of Western North America |last2=Sommer |first2=Robert |last3=Menge |first3=John A. |publisher=University of California Press |year=2012 |isbn=978-0-520-95360-4 |location=Berkeley |pages=143–144 |oclc=797915861}}

= Similar species =

To an untrained eye, O. olivascens appears similar to some chanterelles,{{Cite journal |last=Thiers |first=Harry D. |last2=Arora |first2=David |date=September 1980 |title=Mushrooms Demystified |url=http://dx.doi.org/10.2307/3759750 |journal=Mycologia |volume=72 |issue=5 |pages=1054 |doi=10.2307/3759750 |issn=0027-5514}} but unlike the chanterelle, the jack-o'-lantern mushroom has true, blade-like{{cite book |last1=Meuninck |first1=Jim |title=Foraging Mushrooms Oregon: Finding, Identifying, and Preparing Edible Wild Mushrooms |date=2017 |publisher=Falcon Guides |isbn=978-1-4930-2669-2 |page=4}} gills (rather than ridges) and it can have olive coloration that chanterelles lack; also, Omphalotus species are saprotrophic, grow directly on wood, and are bioluminescent.

Several Omphalotus species with similar bioluminescent properties occur worldwide, all of which are presumed poisonous. The best known are the North American jack o'lantern mushroom (O. olearius) and the tsukiyotake (O. japonicus (Kawam.) Kirchm. & O.K. Mill. (formerly known as Lampteromyces japonicus (Kawam.) Sing.), found in Japan and eastern Asia. Molecular analysis shows the jack-o'-lantern to be most closely related to the ghost fungus O. nidiformis, the colours and shades of which most closely resemble O. olivascens. Additionally, O. illudens is similar.{{Cite book |last=Audubon |title=Mushrooms of North America |publisher=Knopf |year=2023 |isbn=978-0-593-31998-7 |pages=476-477}}

Gymnopilus junonius is another similar-looking species.

Ecology

A saprobe or parasite, O. olivascens is usually found on oak or Eucalyptus, rarely on other hosts.

Omphalotus species cause a white rot by breaking down lignin in their tree hosts.

Toxicity

The jack o'lantern mushroom is poisonous; while not lethal, consuming this mushroom leads to very severe cramps, vomiting, and diarrhea.

The toxic ingredient of many species of Omphalotus is a sesquiterpene compound known as illudin S. This, along with illudin M, have been identified in O. nidiformis. The two illudins are common to the genus Omphalotus and not found in any other basidiomycete mushroom.

References

{{Reflist|refs=

{{cite book |author=Benjamin DR |title=Mushrooms: Poisons and Panaceas — A Handbook for Naturalists, Mycologists and Physicians |publisher=WH Freeman and Company |location=New York, New York |year=1995 |isbn=0-7167-2600-9 |pages=366–67}}

{{cite journal |vauthors=Bigelow HE, Miller OK Jr, Thiers HD |title=A new species of Omphalotus |journal=Mycotaxon |year=1976 |volume=3 |issue=3 |pages=363–372 |url=http://www.cybertruffle.org.uk/cyberliber/59575/0003/003/0363.htm}}

{{cite journal |author=Kirchmair, Martin |title=Identification of illudins in Omphalotus nidiformis and Omphalotus olivascens var. indigo by column liquid chromatography–atmospheric pressure chemical ionization tandem mass spectrometry |journal=Journal of Chromatography A |year=1999 |volume=832 |issue=1–2| pages=247–52 |issn=0021-9673 |doi=10.1016/s0021-9673(98)00892-9|pmid=10070774 }}

{{cite journal |vauthors=Kirchmair M, Morandell S, Stolz D, Pöder R |year=2004 |title=Phylogeny of the genus Omphalotus based on nuclear ribosomal DNA-sequences |journal=Mycologia |volume=96 |issue=6 |pages=1253–1260 |url=http://www.cybertruffle.org.uk/cyberliber/59350/0096/006/1253.htm |doi=10.2307/3762142 |jstor=3762142 |pmid=21148949}}

{{cite web| publisher=California Fungi| title=Omphalotus olivascens|author1=Michael Wood |author2=Fred Stevens |name-list-style=amp | url=http://www.mykoweb.com/CAF/species/Omphalotus_olivascens.html| access-date=2011-03-25}}

{{cite journal |author=Miller OK. Jr. |title=Observations on the genus Omphalotus in Australia |journal=Mycologia Helvetica |year=1994 |volume=6 |issue=2 |pages=91–100}}

{{cite journal |vauthors=Moreno G, Esteve-Raventós F, Pöder R, Ayala N |title=Omphalotus olivascens var. indigo, var. nov. from Baja California (Mexico) |journal=Mycotaxon |year=1993 |volume=48 |pages=217–22 |url=http://www.cybertruffle.org.uk/cyberliber/59575/0048/0217.htm}}

}}