Editing Incertae sedis

{{short description|Term to indicate an uncertain taxonomic position}}
{{Italic title}}
{{Use dmy dates|date=January 2025}}
[[File:Gymnogyps californianus us fish 3.jpg|thumb|[[New World vulture]]s, such as the [[California condor]], were placed ''incertae sedis'' within the class [[Aves]] until the recognition of the new order [[Cathartiformes]].]]
[[File:Plumalina plumaria Hall, 1858 (6.3 cm tall) in quartzose siltstone, weathered from the South Wales Member of the lower Perrysburg Formation (Canadaway Group, Upper Devonian) of western New York State, USA. (8473318685).jpg|thumb|upright|''Plumalina plumaria'' Hall, 1858 (6.3 cm tall), [[Upper Devonian]] of western [[New York State]], US. Workers usually assign this organism to the hydrozoans (phylum ''[[Cnidaria]]'', class [[Hydrozoa]]) or the gorgonarians (phylum Cnidaria, class [[Anthozoa]], order Gorgonaria), but it is probably safest to refer to it as {{lang|la|incertae sedis}}.<ref>{{cite web |url=http://www.jsjgeology.net/Plumalina-plumaria.htm |title=''Plumalina plumaria'' |website=JSJ Geology |access-date=20 January 2021}}</ref>]]
[[File:Varanops BW.jpg|thumb|The [[Varanopidae|varanopids]], a mysterious family of [[tetrapod]]s, had controversial relationships with many other land tetrapods. Paleolontologists have mostly assigned them in the past as [[Eupelycosauria|eupelycosaurian synapsids]]. Others have placed them as [[Basal (phylogenetics)|basal]] [[Neodiapsida|neodiapsids]]. A compromise is to place them as [[Amniota]] {{lang|la|incertae sedis}}.]]
{{langnf|la|'''Incertae sedis'''|of uncertain placement}}<ref name=ICZN>{{cite web |url=http://www.nhm.ac.uk/hosted-sites/iczn/code/index.jsp?booksection=glossary&nfv=true |title=Glossary |work=[[International Code of Zoological Nomenclature]] |publisher=[[International Commission on Zoological Nomenclature]] |access-date=2011-06-12}}</ref> or '''{{lang|la|problematica}}''' is a term used for a [[taxonomy (biology)|taxonomic]] group where its broader relationships are unknown or undefined.<ref>{{cite web |url=http://plants.usda.gov/faq.html |title=Frequently Asked Questions |work=PLANTS database |publisher=[[United States Department of Agriculture]] |access-date=2011-06-12}}</ref> Alternatively, such groups are frequently referred to as "enigmatic taxa".<ref>{{cite book|last= Allaby|first= M.|date= 1999|title= A Dictionary of Zoology|access-date=2013-01-05|publisher= Oxford University Press |page=704 |url= http://www.encyclopedia.com/doc/1O8-enigmatictaxon.html}}</ref> In the system of [[open nomenclature]], uncertainty at specific taxonomic levels is indicated by {{lang|la|incertae familiae}} (of uncertain family), {{lang|la|incerti subordinis}} (of uncertain suborder), {{lang|la|incerti ordinis}} (of uncertain order) and similar terms.<ref name=Matthews1973>{{cite journal |url=http://palaeontology.palass-pubs.org/pdf/Vol%2016/Pages%20713-719.pdf |author=S. C. Matthews |date=1973 |title=Notes on open nomenclature and synonymy lists |journal=[[Palaeontology (journal)|Palaeontology]] |volume=16 |issue=4 |pages=713–719  |url-status=usurped |archive-url=https://web.archive.org/web/20110727162339/http://palaeontology.palass-pubs.org/pdf/Vol%2016/Pages%20713-719.pdf |archive-date=2011-07-27 }}</ref>

== Examples ==
* The fossil plant ''[[Paradinandra|Paradinandra suecica]]'' could not be assigned to any family, but was placed ''incertae sedis'' within the order [[Ericales]] when described in 2001.<ref>{{cite journal |author1=Jürg Schönenberger |author2=Else Marie Friis |author-link2=Else Marie Friis |date=March 2001 |title=Fossil flowers of ericalean affinity from the Late Cretaceous of Southern Sweden |journal=[[American Journal of Botany]] |volume=88 |issue=3 |pages=467–480 | pmid = 11250825 |doi=10.2307/2657112|jstor=2657112 |bibcode=2001AmJB...88..467S }}</ref>
* The fossil ''[[Gluteus minimus (fossil)|Gluteus minimus]]'', described in 1975, could not be assigned to any known animal [[phylum]].<ref name="Davis">{{cite journal |author1=Richard Arnold Davis |author2=Holmes A. Semken Jr. |date=24 January 1975 |title=Fossils of uncertain affinity from the Upper Devonian of Iowa |journal=[[Science (journal)|Science]] |volume=187 |issue=4173 |pages=251–254 |doi=10.1126/science.187.4173.251 |pmid=17838783 |jstor=1739069|bibcode=1975Sci...187..251A |s2cid=39189634 }}</ref> The genus is therefore ''incertae sedis'' within the kingdom [[Animal]]ia.
* While it was unclear to which order the [[New World vulture]]s (family Cathartidae) should be assigned, they were placed in Aves ''incertae sedis''.<ref>{{cite web |author1=J. V. Remsen Jr. |author2=C. D. Cadena |author3=A. Jaramillo |author4=M. Nores |author5=J. F. Pacheco |author6=M. B. Robbins |author7=T. S. Schulenberg |author8=F. G. Stiles |author9=D. F. Stotz |author10=K. J. Zimmer |date=2007 |url=http://www.museum.lsu.edu/~Remsen/SACCBaseline.html |title=A classification of the bird species of South America |work=South American Classification Committee |access-date=2007-10-15 |publisher=[[American Ornithologists' Union]] |archive-url=https://web.archive.org/web/20071010072549/http://www.museum.lsu.edu/~remsen/SACCBaseline.html |archive-date=10 October 2007}}</ref> It was later agreed to place them in a separate order, Cathartiformes.<ref>{{cite web|author1=J. V. Remsen Jr. |author2=C. D. Cadena |author3=A. Jaramillo |author4=M. Nores |author5=J. F. Pacheco |author6=M. B. Robbins |author7=T. S. Schulenberg |author8=F. G. Stiles |author9=D. F. Stotz |author10=K. J. Zimmer |date=2011 |url=http://www.museum.lsu.edu/~Remsen/SACCBaseline.html |title=A classification of the bird species of South America |work=South American Classification Committee |access-date=2011-06-12 |publisher=[[American Ornithologists' Union]]  |archive-url=https://web.archive.org/web/20090302073659/http://www.museum.lsu.edu/~Remsen/SACCBaseline.html |archive-date=2009-03-02 }}</ref>
* [[Bocage's longbill]], ''Motacilla bocagii'', previously known as ''Amaurocichla bocagii'', is a species of [[passerine|passerine bird]] that belongs to the superfamily [[Passeroidea]]. Since it was unclear to which family it belongs, it was classified as Passeroidea ''incertae sedis'', until a 2015 phylogenetic study placed it in ''[[Motacilla]]'' of [[Motacillidae]].<ref>{{cite journal|author=Per Alström |author2=Knud A. Jønsson |author3=Jon Fjeldså |author4=Anders Ödeen |author5=Per G. P. Ericson |author6=Martin Irestedt |title=Dramatic niche shifts and morphological change in two insular bird species|journal=[[Royal Society Open Science]]|date=2015|volume=2|issue=3|page=140364|doi=10.1098/rsos.140364|pmid=26064613|pmc=4448822|bibcode=2015RSOS....240364A}}</ref><ref>{{cite journal|author1=Rebecca B. Harris |author2=Per Alström |author3=Anders Ödeen |author4=Adam D. Leaché |title=Discordance between genomic divergence and phenotypic variation in a rapidly evolving avian genus (Motacilla)|journal=[[Molecular Phylogenetics and Evolution]]|date=2018|volume=120|pages=183–195|doi=10.1016/j.ympev.2017.11.020|pmid=29246816|arxiv=1707.03864|bibcode=2018MolPE.120..183H |s2cid=3592799}}</ref>
* ''[[Parakaryon myojinensis]]'', a single-celled organism that is apparently distinct from [[Prokaryote|prokaryotes]] ''and'' [[Eukaryote|eukaryotes]], being the only identified species with a completely unknown position within the [[tree of life (biology)|tree of life]].<ref>{{cite journal | last1 = Yamaguchi | first1 = Masashi | display-authors = etal | title = Prokaryote or eukaryote? A unique microorganism from the deep sea | journal = Microscopy | date = 28 September 2012 | volume = 61 | issue = 6 | pages = 423–431 | doi = 10.1093/jmicro/dfs062 | pmid = 23024290}}</ref>
* [[Biological dark matter]], genetic material produced from unidentified microorganisms that appears to match no known species. Like ''Parakaryon'', its producers' positions in the tree of life are completely unknown.
* ''[[Metallogenium]]'' is a bacterium that can form star-shaped minerals.<ref>{{cite book |editor=Joachim Reitner & Volker Theil |date=2011 |author=Joachim Reitner |chapter=''Metallogenium'' |title=Encyclopedia of Geobiology |pages=563–565 |doi=10.1007/978-1-4020-9212-1_220 |publisher=[[Springer Science+Business Media|Springer]] |isbn=978-1-4020-9211-4|series=Encyclopedia of Earth Sciences Series |bibcode=2011enge.book.....R }}</ref>
* [[Circothecidae]] are a family of [[Cambrian]] animals, sometimes attributed to the [[Hyolitha]], though some authors suggest (on the basis of no specified evidence) that they are definitely not.
* The [[Titanomis|frosted phoenix]] moth (''Titanomis sisyrota'') is so rare and so obscure it is unable to be placed in any family within the [[Lepidoptera]].

==In formal nomenclature==
When formally naming a taxon, uncertainty about its taxonomic classification can be problematic. The [[International Code of Nomenclature for algae, fungi, and plants]], stipulates that "species and subdivisions of genera must be assigned to genera, and infraspecific taxa must be assigned to species, because their names are combinations", but ranks higher than the [[genus]] may be assigned ''incertae sedis''.<ref name=ICN>{{cite book |author1=McNeill, J. |author2=Barrie, F.R. |author3=Buck, W.R. |author4=Demoulin, V. |author5=Greuter, W. |author6=Hawksworth, D.L. |author7=Herendeen, P.S. |author8=Knapp, S. |author9=Marhold, K. |author10=Prado, J. |author11=Prud'homme Van Reine, W.F. |author12=Smith, G.F. |author13=Wiersema, J.H. |author14=Turland, N.J. |date=2012 |volume=Regnum Vegetabile 154 |title=International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 |publisher=A.R.G. Gantner Verlag KG  |isbn=978-3-87429-425-6 |url=http://www.iapt-taxon.org/nomen/main.php?page=art3 |access-date=2013-07-28}}</ref>

==Reason for use==
===Poor description===
This excerpt from a 2007 [[Academic publishing|scientific paper]] about [[crustacean]]s of the [[Kuril–Kamchatka Trench]] and the [[Japan Trench]] describes typical circumstances through which this category is applied in discussing:<ref>{{cite journal |author=Graham J. Bird |date=2007  |journal=[[Zootaxa]] |volume=1599 |pages=121–149 |url=http://www.mapress.com/zootaxa/2007f/zt01599p149.pdf  |title=Family ''incertae cedis''|doi=10.11646/zootaxa.1599.1.8}}</ref>
<blockquote>...the removal of many genera from new and existing families into a state of incertae sedis. Their reduced status was attributed largely to poor or inadequate descriptions but it was accepted that some of the vagueness in the analysis was due to insufficient character states. It is also evident that a proportion of the characters used in the analysis, or their given states for particular taxa, were inappropriate or invalid. Additional complexity, and factors that have misled earlier authorities, are intrusion by extensive [[homoplasies]], apparent character state reversals and [[convergent evolution]].</blockquote>

===Not included in an analysis===
If a formal [[phylogeny|phylogenetic]] analysis is conducted that does not include a certain taxon, the authors might choose to label the taxon ''incertae sedis'' instead of guessing its placement. This is particularly common when [[molecular phylogeny|molecular phylogenies]] are generated, since tissue for many rare organisms is hard to obtain. It is also a common scenario when [[fossil]] taxa are included, since many fossils are defined based on partial information. For example, if the phylogeny was constructed using soft tissue and [[vertebra]]e as principal characters and the taxon in question is only known from a single tooth, it would be necessary to label it ''incertae sedis''.<ref name=Matthews1973/>

=== Controversy ===
If conflicting results exist or if there is not a consensus among researchers as to how a taxon relates to other organisms, it may be listed as ''incertae sedis'' until the conflict is resolved.<ref name=Matthews1973/>

== Phylogenetic vs. nomenclatural uncertainty ==
The term ''incertae sedis'' refers to uncertainty about phylogenetic position of a taxon, which may be expressed, among others, by using a question mark after or before a taxon name. This should be distinguished from the situation where either it is uncertain how to use a name, often because the types have been lost (''[[nomen dubium]]'', ''[[species inquirenda]]''), or whether a poorly preserved specimen should be included within a given species or genus, which is often expressed using a 'cf.' (from Latin ''confer'', compare, before a taxon name); such a convention is especially widespread in palaeontology.<ref>{{Cite journal |last1=Bengtson |first1=Peter |date=January 1988 |title=Open Nomenclature |journal=[[Palaeontology (journal)|Palaeontology]] |volume=1 |issue=31 |pages=223–227 |url=https://www.palass.org/sites/default/files/media/publications/palaeontology/volume_31/vol31_part1_pp223-227.pdf}}</ref>

== In zoological nomenclature ==
In zoological nomenclature, "''incertae sedis''" is not a nomenclatural term at all ''per se'', but is used by taxonomists in their classifications to mean "of uncertain taxonomic position".<ref name=ICZN/><sup>Glossary</sup> In botany, a name is not validly published if it is not accepted by the author in the same publication.<ref name=ICN/><sup>Article 36.1</sup> In zoology, a name proposed conditionally may be [[available name|available]] under certain conditions.<ref name=ICZN/><sup>Articles 11 and 15</sup> For uncertainties at lower levels, some authors have proposed a system of "open nomenclature", suggesting that question marks be used to denote a questionable assignment.<ref name=Matthews1973/> For example, if a new species was given the [[specific name (botany)|specific epithet]] ''album'' by Anton and attributed with uncertainty to ''Agenus'', it could be denoted "''Agenus''? ''album'' Anton (?Anton)"; the "(?Anton)" indicates the author that assigned the question mark.<ref name=Matthews1973/> So if Anton described ''Agenus album'', and Bruno called the assignment into doubt, this could be denoted "''Agenus''? ''album'' (Anton) (?Bruno)", with the parentheses around Anton because the original assignment (to ''Agenus'') was modified (to ''Agenus''?) by Bruno.<ref name=Matthews1973/> This practice is not included in the [[International Code of Zoological Nomenclature]], and is used only by paleontologists.<ref name=Matthews1973/>

==See also==
* [[Glossary of scientific naming]]
* ''[[Nomen dubium]]'', a name of unknown or doubtful application
* ''[[Species inquirenda]]'', a species that in the opinion of the taxonomist requires further investigation
* [[Wastebasket taxon]]
* [[Sui generis#Biology|''Sui generis'' (biology)]]
* [[Unclassified language]]

== References ==
{{reflist|32em}}

== External links ==
* {{wiktionary-inline}}
* {{Commons category-inline |Incertae sedis |''incertae sedis''}}

{{Life on Earth}}
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{{Bacteria classification}}
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[[Category:Incertae sedis| ]]
[[Category:Biological nomenclature]]
[[Category:Taxonomy (biology)]]
[[Category:Zoological nomenclature]]