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Categorization of taxa articles

Wikipedia[a] contains around 400,000[1] articles about taxa (groups of animals, plants etc). This essay contains information about how such articles are currently categorized and guidance for editors about categorizing them.[b]

Categories that are based purely on taxonomy (e.g. Category:Mammals) are generally well populated (i.e. most/all of the relevant articles are in the category), but other categories in which taxa articles are placed (e.g. a "Spiders of Latvia" category) are often very underpopulated (and may also have unclear inclusion criteria).

The essay is intended to assist editors to efficiently and consistently categorize articles in a way that is useful (to readers and editors). Many categories for taxa that have been created and partly populated have later been deleted.


Taxa articles

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Most taxa articles are about a species; some are about a subspecies, a genus or a higher taxonomic group. Some are well-developed articles, but many are very short articles (in some cases a single sentence[2]).

Conventions used in this essay

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In this essay italic font indicates a reference to a deletion discussion.

Characteristics used to categorize taxa

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The ways in which taxa articles (for example, an article about a species of fish) are currently[c] categorized include those listed below. In this section each characteristic (or group of characteristics) has been identified by a one-letter code.

  • b. By position in the biological tree of life (ToL) -
    • E.g. Category:Mammals
    • Note: There are probably few (if any) articles about taxa that are not categorized by this characteristic.[d]
    • Note: This characteristic is referred to in the notes below as "type of organism".
  • g. By the geological period(s) when the organism was alive -
  • By categories (some hidden by default) that are added by templates - e.g. stub categories and maintenance categories. The talk pages of taxa articles are also categorized (e.g. to indicate which wikiprojects cover the article).

Many of these categories are very incomplete. For example, (as of 2020) about 10% of the articles about fungi are in subcategories of Category:Fungi by edibility.[5]

Intersection categories

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In this section 2-letter and 3-letter codes (based on the 1-letter codes defined in the section above) are used to refer to the combinations of characteristics.

Intersection categories based on 2 characteristics one of which is type of organism include -

Intersection categories based on 2 characteristics (not including type of organism) include -

Intersection categories based on 3 or more characteristics include -

Note: Do not create new types of intersection categories (e.g. Category:Taxa named by Carl Linnaeus that are now extinct) without careful consideration and discussion with other editors.

Note: Petscan can be used to find articles that are at the intersection of 2 categories - e.g. Hymenoptera described in 2017, but very few readers (and not all editors) know about it.[i]

section under development
                  2 characteristics
   c  d  e  f  g  h  l  n  o  p  r  s  t  u  v  x  y
b bc bd be bf bg bh bl bn bo bp br bs bt bu bv bx by
c  . cd ce cf cg ch cl cn co cp cr cs ct cu cv cx cy
d  cd . de df dg dh dl dn do dp dr ds dt du dv dx dy
e  ce de . ef eg eh el en eo ep er es et eu ev ex ey
f  cf df ef . fg fh fl fn fo fp fr fs ft fu fv fx fy
g  cg dg eg fg . gh gl gn go gp gr gs gt gu gv gx gy
h  ch dh eh fh gh . hl hn ho hp hr hs ht hu hv hx hy
l  cl dl el fl gl hl . ln lo lp lr ls lt lu lv lx ly
n  cn dn en fn gn hn ln . no np nr ns nt nu nv nx ny
o  co do eo fo go ho lo no . op or os ot ou ov ox oy
p  cp dp ep fp gp hp lp np op . pr ps pt pu pv px py
r  cr dr er fr gr hr lr nr or pr . rs rt ru rv rx ry
s  cs ds es fs gs hs ls ns os ps rs . st su sv sx sy
t  c  d  e  f  g  h  l  n  o  p  r  s  .  u  v  x  y
u  c  d  e  f  g  h  l  n  o  p  r  s  t  .  v  x  y
v  c  d  e  f  g  h  l  n  o  p  r  s  t  u  . --  y
x  c  d  e  f  g  h  l  n  o  p  r  s  t  u --  .  y
y  c  d  e  f  g  h  l  n  o  p  r  s  t  u  v  x  .
            3 characteristics (including b)

Guidance for editors working on taxa articles

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Editors should follow all the general rules regarding categorizing articles (e.g. don't place an article (directly) in 2 categories where one is a parent of the other). Some specific guidance:

  • Don't place an article in a category unless the relevant information is in the article (and ideally, referenced).
  • Don't leave an article uncategorized.[6] As a minimum the article should be categorized for the genus etc.
  • Check whether the relevant wikiproject has any guidance about the categorization of articles within its remit. For example, there's Wikipedia:WikiProject Gastropods/Categories and Wikipedia:WikiProject Fishes/Categories.
  • You are under no obligation to consider every possible characteristic (and combination of characteristics) of an article's topic to see if there's a corresponding category.[j]
  • If an organism is important to a particular country, tribe, club etc (e.g. by being an important foodstuff for that group or by being used as a symbol) then it may be appropriate to mention that fact in the text of the article about the organism, but that should not be used to categorize the article about the organism.
  • Where there is an article (or even a category) specifically about use of an organism as a symbol etc (e.g. Doves as symbols) then that article should be placed in the category for the type of organism (TBC).

Guidance for editors working on the category structure

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Editors working on the category structure for taxa articles should follow all the general rules regarding category structures (e.g. rules that prevent category loops). Some specific guidance:

  • Taxonomical jargon (terms that might not be known by non-specialists) should not be used in the names of intersection categories. E.g. avoid categories with names such as "Deuterostomes of Asia".[7]
  • Terms that are unclear (e.g. "wildlife")[8] should be avoided.
  • Categories that are named for a taxon may contain articles that are not about taxa. For example:
  • There are cases where a category should not be placed in all the same categories as the article of the same name. For example, the Bilaterians article belongs in Category:Subkingdoms, but Category:Bilaterians (which contains articles about species etc) does not belong in Category:Subkingdoms.
  • Don't create a category unless you intend to populate it (by re-categorizing articles from the parent categories). I.e. don't expect other editors to do it.
  • Follow any relevant guidance e.g. Wikipedia:WikiProject Plants/Categorization.
  • Don't create a category that isn't part of an existing categorization scheme without consulting with other editors at the relevant wikiproject.
  • Petscan can be used to detect problems in the category structure, e.g. -
  • That a category is mentioned in this essay does not mean that the category should exist. Indeed, this essay may help to identify categories that should be deleted.
  • Do not create any category based on characteristics of the named of organisms - e.g. Toadlets, Organisms named after....

Guidance about specific areas

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  • Fish - In "correct" English many fish are "fish", many species of fish are "fishes". However, in Wikipedia categorization we've standardized on using "fish".[10][k]
  • Extinct organisms ... There are also categories such as Category:Fossils of Brazil.

Appendix A - Levels

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The table below shows (using mice as an example) which taxonomic levels are used in different places in the category structure.

Note: This table is intended to have words in blue (linked to a category) and "X"s in red (indicating no category) - assuming there are no category redirects. Any words in red or "X"s in blue indicate a change to the category structure since the table was created/updated (i.e. the table should be updated).

T Prehistoric t Extinct t T of Africa Mesozoic t of Africa
Organisms life taxa Biota life
Eukaryotes eukaryotes X X X
Animals animals animals Fauna animals
Bilaterians X X X X
Deuterostomes deuterostomes X X X
Chordates chordates chordates X X
Vertebrates vertebrates vertebrates Vertebrates vertebrates
Teleostomi X X X X
Tetrapods tetrapods X X tetrapods
Amniotes X X X X
Synapsids synapsids X X synapsids
Therapsids therapsids X X X
Mammals mammals mammals Mammals mammals
X eutherians X X X
X placental mammals X X X
Rodents rodents rodents Rodents X
Muroid rodents X X X X
Muridae murids X X X X XX

Link to table: User:DexDor/BioCat/TemplateA

Note: The number of levels in the category structure may be greater than the number of levels shown here because the category structure also includes "...by classification" categories. For example, between Category:Rodents and Category:Mammals there is Category:Mammals by classification.

Categorization of redirects

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See discussion at a user talk page

See also

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Notes

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  1. ^ Note: In this essay all references to "Wikipedia" refer to the English language Wikipedia unless otherwise specified.
  2. ^ Note: The intention is that over time this is changed from an essay describing what has happened into a guidance page.
  3. ^ The English language Wikipedia as of 2019
  4. ^ The Neocrinus decorus article was not categorized below the animals level prior to 2020.
  5. ^ WP:FishCat (as of February 2020) and categorization advice for plant articles (WP:WGSRPD) which says "Higher taxa are included only if endemic (for example, a genus endemic to Western Australia could have the genus article itself included in that category).".
  6. ^ Re whether the year that a human cataloged an animal is defining at all - one editor's view is "I think it can be a useful way of covering the development of the scientific field. I agree that it's less relevant for the subject directly, although it does indicate the closeness of the animal's relation to humans." (a CFD in 2014).
  7. ^ Note: This categorization is not used for articles about species.
  8. ^ Note: A CFD in 2014 deleted some categories at this intersection.
  9. ^ Ideally there would be a reader friendly category search tool linked in the left-hand panel, and we could deprecate intersection categories altogether.
  10. ^ e.g. Category:Butterfly food plants
  11. ^ The relevant wikiproject is WikiProject Fishes so there's Category:A-Class Fishes articles etc.

References

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  1. ^ Around 400,000 (as of February 2020) is based on the number of pages in Category:Articles with 'species' microformats. This is over 6% of the encyclopedia's articles.
  2. ^ E.g. This article is a single sentence 10 years after it was created.
  3. ^ CFD, but there are categories such as Category:Miocene species extinctions.
  4. ^ E.g. Brassica rapa.
  5. ^ The 10% value is calculated from the number of pages in the category tree (approximately 1300) and the number of taxon articles tagged by WikiProject Fungi (approximately 12500).
  6. ^ From WP:Category - "Every Wikipedia page should belong to at least one category. (However, ....)"
  7. ^ E.g. see this 2018 CFD
  8. ^ CFD discussion in 2006
  9. ^ This is consistent with elsewhere in Wikipedia - e.g. Category:Fictional detectives is under Category:Detectives.
  10. ^ See for example this 2014 discussion and this 2011 discussion.