Editing Secotioid

{{Short description|Type of fungi}}
[[Image:Weraroa novae zelandiae.jpg|150 px|right|thumb|''[[Psilocybe weraroa]]'', a secotioid form of a bluing ''[[Psilocybe]]'' in the cyanescens complex.]]

'''Secotioid''' fungi produce an intermediate fruiting body form that is between the mushroom-like [[hymenomycete]]s and the closed bag-shaped [[gasteroid fungi|gasteromycetes]], where an evolutionary process of '''gasteromycetation''' has started but not run to completion.  Secotioid fungi may or may not have opening caps, but in any case they often lack the vertical [[geotropism|geotropic]] orientation of the [[hymenophore]] needed to allow the spores to be dispersed by wind, and the [[basidiospores]] are not forcibly discharged or otherwise prevented from being dispersed (e.g. gills completely inclosed and never exposed as in the secotioid form of ''[[Lentinus tigrinus]]'')—note—some mycologists do not consider a species to be secotioid unless it has lost [[ballistospory]].<ref name="Hibbett_1994"/>

==Explanation of secotioid development and gasteromycetation==

Historically [[agarics]] and [[boletes]] (which bear their spores on a [[hymenium]] of gills or tubes respectively) were classified quite separately from the [[gasteroid fungi]], such as [[puff-balls]] and [[truffles]], of which the spores are formed in a large mass enclosed in an outer skin.  However, in spite of this apparently very great difference in form, recent mycological research, both at microscopic<ref name=thiers/> and molecular<ref name=Hibbett/> level has shown that sometimes species of open mushrooms are much more closely related to particular species of gasteroid fungi than they are to each other.  Fungi which do not open up to let their spores be dispersed in the air, but which show a clear [[Morphology (biology)|morphological]] relation to agarics or boletes, constitute an intermediate form and are called '''secotioid'''.<ref name=thiers/>

The word is derived from the name of the genus ''[[Secotium]]'', which was defined in 1840 by [[Gustav Kunze|Kunze]] for a South African example, ''S. gueinzii'', which is the type species.  In the following years numerous secotioid species were added to this genus, including ones which according to modern taxonomy belong to other genera or families.<ref name=Conard/><ref name=SFSecotium/><ref name=IFSecotium/>

On a microscopic scale, secotioid fungi do not expel their spores forcibly from the basidium; their spores are "statismospores".  Like gasteroid fungi, secotioid species rely on animals such as rodents or insects to distribute their spores.

It can at times be disadvantageous for a mushroom to open up and free its spores in the usual way.  If this development is aborted, a secotioid form arises, perhaps to be followed eventually by an evolutionary progression to a fully gasteroid form.  This type of progression is called '''gasteromycetation''' and seems to have happened several times independently starting from various genera of "normal" mushrooms.  This means that the secotioid and also the gasteroid fungi are [[polyphyletic]].  According to the paper by Thiers,<ref name=thiers/> in certain climates and certain seasons, it may be an advantage to remain closed, because moisture can be conserved in that way.

[[File:Brockhaus and Efron Encyclopedic Dictionary b11 168-5.jpg|thumb|130px|left|Cross-section of ''Hymenogaster tener'']]
For example, the gasteroid genus ''[[Hymenogaster]]'' has been shown to be closely related to agaric genera such as ''[[Hebeloma]]'', which were formerly placed in family [[Cortinariaceae]] or [[Strophariaceae]].  This is found by DNA analysis and also indicated on a microscopic scale by the resemblance of the spores and basidia.  According to a current classification system, ''Hebeloma'' now belongs to family [[Hymenogastraceae]], and is considered more narrowly related to the closed ''[[Hymenogaster]]'' fungi than, for instance, to the ordinary mushrooms in genus ''[[Cortinarius]]''.<ref name=Binder/><ref name=Francis/>

A similar case is the well-known "Deceiver" mushroom ''[[Laccaria laccata]]'' which is now classified in the ''[[Hydnangiaceae]]'', ''Hydnangium'' being a gasteroid genus.

It has been found that a change in a single locus of a gene of the gilled mushroom ''[[Lentinus tigrinus]]'' causes it to have a closed fruiting body.  This suggests that the emergence of a secotioid species may not require many mutations.<ref name=Hibbett/>

There is a spectrum of secotioid species ranging from the open form to the closed form in the following respects:
*there may be an evident stipe, or there may be only a remnant consisting of a column of non-fertile tissue,
*if there is a stipe the edge of the cap may separate from it (partially opening), or may not,
*there may be recognizable gills (though oriented in all directions and very convoluted), or the fertile interior may be uniform like the [[gleba]] of gasteroid fungi, and
*the spore-bearing tissue may be above ground ([[epigeous]]), or underground ([[wikt:hypogeous|hypogeous]]), or partly buried.

The adjective "'''sequestrate'''" is sometimes used as a general term to mean "either secotioid or gasteroid".

==Examples==
''[[Cortinarius]]'' is a very widespread genus of agarics, but also contains some secotioid species, such as ''C. leucocephalus'', ''C. coneae'' and ''C. cartilagineus''.

[[File:Pholiota nubigena (Harkn.) Redhead 352483.jpg|thumb|130px|right|''Pholiota nubigena'']]
''[[Pholiota nubigena]]'' is a secotioid species found early in the year at high altitude in the western United States.  It was originally assigned to ''[[Secotium]]'' and later to a more specific secotioid genus ''Nivatogastrium'', but in fact it is closely allied to ''[[Pholiota squarrosa]]''<ref name=thiers/> and it has now been moved to genus ''[[Pholiota]]'' itself, although the latter consists primarily of [[agaric]]s.<ref name=Nivatogastrium1/><ref name="Matheny 2007"/><ref name=SFnubigena/>

''[[Gastroboletus]]'' is a secotioid [[bolete]] genus where the fruiting bodies may or may not open, but in any case the tubes are not aligned vertically as in a true bolete.<ref name=thiers/>

Secotioid mushrooms of the genus ''[[Endoptychum]]'' (such as ''E. agaricoides'', ''E. arizonicum'') have been now moved to genus ''[[Chlorophyllum]]'', closely related to ''[[Macrolepiota]]''. 

[[File:Agaricus deserticola G. Moreno, Esqueda & Lizárraga 762174.jpg|thumb|130px|left|''Agaricus deserticola'']]
''[[Agaricus deserticola]]'' is a secotioid species of ''[[Agaricus]]'' (the genus of common cultivated mushrooms) which at one time was placed in the genus ''Secotium''. Similarly, ''[[Agaricus inapertus]]'' was formerly known as ''Endoptychum depressum'' until [[molecular phylogenetics|molecular]] analysis revealed it to be closely aligned with ''Agaricus''.<ref name=Vellinga2003/>

==References==
{{Reflist|refs=
<ref name=Binder>{{Cite journal | author-link = M. Binder & A. Bresinsky | title = Derivation of a polymorphic lineage of Gasteromycetes from boletoid ancestors | journal = Mycologia | volume = 94 | issue = 1  | pages = 85–98 | publisher = The New York Botanical Garden, Bronx. NY 10458 | location = New York | year = 2002 | url = http://www.mycologia.org/cgi/content/full/94/1/85 | doi=10.2307/3761848 | pmid=21156480| last1 = Binder | first1 = M | last2 = Bresinsky | first2 = A | jstor = 3761848 }}</ref>

<ref name=Conard>{{Cite journal | author-link = Henry S. Conard | title = The Structure and Development of Secotium agaricoides | journal = Mycologia | volume = 7 | issue = 2  | pages = 94–104 | publisher = The New York Botanical Garden, Bronx. NY 10458 | location = New York | date = March 1915 | url = http://www.mykoweb.com/systematics/literature/The%20Secotioid%20Syndrome.pdf | doi=10.2307/3753132| jstor = 3753132 | last1 = Conard | first1 = Henry S }}</ref>

<ref name=Francis>{{Cite journal | title = Historical and current perspectives in the systematics of Australian cortinarioid sequestrate (truffle-like) fungi. | journal = Australasian Mycologist | volume = 21 | issue = 3  | pages = 81–116 | year = 2002 | url = http://bugs.bio.usyd.edu.au/AustMycolSoc/Journal/2002/21_3_b.pdf }}</ref>

<ref name=Hibbett>{{Cite journal | author-link = David S. Hibbett et al. | title = Evolution of gilled mushrooms and puffballs inferred from ribosomal DNA sequences | journal = PNAS | volume = 94 | issue = 22  | pages = 12002–12006 | publisher = National Academy of Sciences of the United States of America | location = Washington DC | date = 1997-10-28 | doi=10.1073/pnas.94.22.12002 | pmid=9342352 | pmc=23683| last1 = Hibbett | first1 = D. S | last2 = Pine | first2 = E. M | last3 = Langer | first3 = E | last4 = Langer | first4 = G | last5 = Donoghue | first5 = M. J | bibcode = 1997PNAS...9412002H | doi-access = free }}</ref>

<ref name=Hibbett_1994>{{cite journal |author1=Hibett DS |author2=Tsuneda A |author3=Shigeyuki M. |year= 1994 |title=The Secotioid Form of ''Lentinus tegrinus'':Genetics and Development of a Fungal Morphological Innovation. |journal=American Journal of Botany |volume=81 |issue=4 |pages=466–478 |doi=10.2307/2445497|jstor=2445497 }}</ref>

<ref name=IFSecotium>For genus ''Secotium'', also see {{cite web |url=http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=39251 |title=the ''Secotium'' Kunze page |work=Index Fungorum |publisher=Royal Botanic Gardens Kew |accessdate=2022-06-18 }}  </ref>

<ref name="Matheny 2007">{{cite journal |vauthors=Matheny PB, Curtis JM, Hofstetter V, Aime MC, Moncalvo JM, Ge ZW, Yang ZL, Slot JC, Ammirati JF, Baroni TJ, Bougher NL, Hughes KW, Lodge DJ, Kerrigan RW, Seidl MT, Aanen DK, DeNitis M, Daniele GM, Desjardin DE, Kropp BR, Norvell LL, Parker A, Vellinga EC, Vilgalys R, Hibbett DS |title=Major clades of Agaricales: a multilocus phylogenetic overview |journal=Mycologia |volume=98 |issue=6 |year=2007 |pages=982–95 |doi=10.3852/mycologia.98.6.982 |pmid=17486974|url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=349&content=PDF }} {{open access}}</ref>

<ref name=Nivatogastrium1>See [http://www.mykoweb.com/CAF/species/Nivatogastrium_nubigenum.html this Mykoweb page] of ''Nivatogastrium nubigenum'', which shows rudimentary lamellae.</ref>

<ref name=SFnubigena>{{cite web |url=http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=550583 |title=the ''Pholiota nubigena'' page |work=Species Fungorum |publisher=Royal Botanic Gardens Kew |access-date=2020-05-24 }}  </ref>

<ref name=SFSecotium>To see which species of ''Secotium'' have been assigned to a new (presumably more appropriate) genus and which remain under that taxon, see {{cite web |url=https://www.speciesfungorum.org/Names/Names.asp |title=the Species Fungorum search page |work=Species Fungorum |publisher=Royal Botanic Gardens Kew |accessdate=2022-06-18 }}  Then select "genus" and search for ''Secotium''.</ref>

<ref name=thiers>The following 1984 article provides a good introduction to sectioid fungi: {{Cite journal | author-link = Harry D. Thiers | title = The Secotioid Syndrome | journal = Mycologia | volume = 76 | issue = 1  | pages = 1–8 | publisher = The New York Botanical Garden, Bronx. NY 10458 | location = New York | date = January–February 1984 | url = http://www.mykoweb.com/systematics/literature/The%20Secotioid%20Syndrome.pdf | doi=10.2307/3792830| jstor = 3792830 | last1 = Thiers | first1 = Harry D }}</ref>

<ref name=Vellinga2003>{{cite journal |author1=Vellinga EC |author2=de Kok RPJ |author3=Bruns TD. |title=Phylogeny and taxonomy of ''Macrolepiota'' (Agaricaceae) |journal=Mycologia |year=2003 |volume=95 |issue=3 |pages=442–56 |url=http://www.cybertruffle.org.uk/cyberliber/59350/0095/003/0442.htm |doi=10.2307/3761886 |pmid=21156633|jstor=3761886 }}</ref>
}}

[[Category:Mycology]]
[[Category:Fungal morphology and anatomy]]
[[Category:Mushroom types]]
[[Category:Secotioid fungi| ]]