User:DexDor/BioCat


 * Categorization of taxa articles

Wikipedia contains around 400,000 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.

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.

Ultimately a species article should look the same and be categorized the same, whether it's a mollusc or moth.

Taxa articles
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 ).

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

Characteristics used to categorize taxa
The ways in which taxa articles (for example, an article about a species of fish) are currently 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.
 * Note: This characteristic is referred to in the notes below as "type of organism".


 * c. By capabilities that the organism does or does not have -
 * Category:Flightless birds
 * Category:Low light plants
 * Category:Rolling animals
 * Category:Venomous animals etc
 * Category:Live-bearing fish etc
 * Note: Some categories for characteristics like this have been deleted - e.g. Magnetoreceptive animals, Animal dance, Venomous spiders, Animals that can change color, ... that resemble twigs, Birds with red bill or beak.


 * d. By the organism's diet -
 * Category:Carnivores etc
 * Category:Hematophages etc


 * e. By edibility to humans -
 * Category:Edible molluscs etc
 * Category:Inedible fungi etc
 * Category:Commercial molluscs etc
 * Category:Medicinal plants etc
 * Category:Psychoactive cacti etc
 * Note: Categories that have been deleted include Edible fish by habitat, Poisonous fish, Poisonous plants, etc.


 * f. By first appearance of the taxon -
 * Category:Late Jurassic first appearances etc


 * g. By the geological period(s) when the organism was alive -
 * Category:Mesozoic life etc
 * Note: Some articles have been placed in many categories based on this characteristic (example).
 * Note: Categories that have been deleted include Holocene animals.


 * h. By habitat -
 * Category:Cave organisms etc
 * Category:Cold water fish etc
 * Category:... coastal fauna etc
 * Category:Mangrove fauna etc
 * Note: Categories that have been deleted include Euryhaline fish, Urban animals.


 * l. By level of taxonomic rank -
 * Category:Genera etc
 * Category:Infraspecific virus taxa
 * Note: Species articles should not be categorized for that characteristic.
 * Note: See guidance from WikiProject Plants.


 * n. By the person who named the taxon -
 * Category:Taxa named by Carl Linnaeus etc
 * Note: Categories that have been deleted include Microscopic organisms described by ..., Toadlets, Cardinals (birds), Organisms named after....


 * o. By other characteristics -
 * Some articles about species etc have been placed in Category:Space-flown life.
 * Note: Categories that have been deleted include Sequenced genomes, Living fossils, Primitive fish, Indicator species, Solitary Animals.
 * Note: Articles about species etc should not be placed in Category:National symbols of Togo etc (that is not a defining characteristic of a species).


 * p. By how the organism is a pest -
 * Category:Venomous animals
 * Category:Garden pests etc
 * Note: Categories that have been deleted include Poisonous amphibians, Dangerous spiders, Biting insects, Animals that prey on humans, Man eaters.


 * r. By the regions in which the organism is/was native (i.e. the range/distribution) -
 * Category:Cosmopolitan species etc (see cosmopolitan distribution)
 * Category:Palearctic Lepidoptera etc
 * Category:Biota of the Indian Ocean etc
 * Category:Biota of Africa etc
 * Category:Endemic fauna of Alaska etc
 * Category:... taxa restricted to the Afrotropics
 * Note: For articles about taxa at the rank of genus or higher there is specific guidance to only categorize if endemic.
 * Note: Categories that have been deleted include Invertebrates of Croatia, Indo-Pacific fauna, Fauna of Liechtenstein, Fauna of Ceuta, Restricted-range endemic bird species.
 * Note: For more details see User:DexDor/BioGeoCat.


 * s. By size -
 * Category:Microorganisms etc
 * Note: Categories that have been deleted include Megafauna.


 * t. By characteristics of the taxonomy -
 * Category:Obsolete taxa etc
 * Category:Historically recognized plant taxa etc (is this the same as obsolete?)
 * Category:Monotypic taxa etc
 * Category:Incertae sedis etc
 * Category:Undescribed species etc
 * Category:Paraphyletic groups and Category:Polyphyletic groups (plus Category:Common names of organisms)
 * Note: Categories that have been deleted include Lazarus taxa, Available gastropod names, Snakes by taxonomic synonyms.


 * u. By ways in which they are used by humans (other than being eaten) -
 * Category:Ornamental plants etc
 * Category:Domesticated birds etc
 * Note: Categories that have been deleted include Fly fishing target species, Pet reptiles, Commercially available Elms, Cold-water aquarium fish, Pollinator birds.


 * v. By vulnerability of the taxon -
 * Category:Species endangered by mangrove destruction etc
 * Category:IUCN Red List least concern species etc
 * Category:NatureServe critically imperiled species etc
 * Category:ESA endangered species etc
 * Note: Categories that have been deleted include Seafood red list.


 * x. By extinction of the taxon -
 * Category:Prehistoric fish etc
 * Category:Extinctions since 1500 etc


 * y. By year of description -
 * Category:Taxa described in 1758 etc Note: There is guidance from WikiProject Plants about these categories.


 * By various combinations of the above characteristics (intersection categories) - e.g. Category:Extinct birds of New Zealand. See separate section below.


 * 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.

Intersection categories
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 -
 * Category:Venomous fish (bc)
 * Category:Carnivorous fungi (bd)
 * Category:Edible molluscs (be)
 * Category:Triassic crustaceans (bg)
 * Category:Cave beetles (bh)
 * Category:Primate genera (bl)
 * Category:Parasitic vertebrates (bo)
 * Category:Catfish of Asia (br)
 * Category:Microscopic animals (bs)
 * Category:Obsolete gastropod taxa (bt)
 * Category:Wool animals (bu)
 * Category:Least concern plants (bv)
 * Category:Mammal extinctions since 1500 (bx)
 * Category:Fish described in 1758 (by).

Intersection categories based on 2 characteristics (not including type of organism) include -
 * Category:Clawed herbivores (cd)
 * Category:Aposematic species (cl)
 * Category:Tithonian genus first appearances (fl)
 * Category:Mesozoic life of Europe (gr)
 * Category:Western North American coastal fauna (hr)
 * Category:Monotypic genera (lt)
 * Category:Higher-level bird taxa restricted to the Afrotropics (lr)
 * Category:Extinct biota of Africa (rx)
 * Category:Least concern biota of Africa etc (vr)
 * Category:Extant Pliocene first appearances (xf)
 * Category:Prehistoric life genera (xl)
 * Note: some combinations are not valid - e.g. vx. Some other combinations are not used - e.g. px, ux

Intersection categories based on 3 or more characteristics include -
 * Category:Extinct flightless birds (xcb,cx)
 * Category:Mesozoic fish of Europe (gbr,gr)
 * Category:Insect pests of tropical forests (bph,hp)
 * Category:Freshwater fish of South Asia (hbr,hr)
 * Category:Monotypic Euphorbiaceae genera (tbl,lt)
 * Category:Prehistoric primate genera (bxl,lx)
 * Category:Extinct birds of New Zealand (xbr,rx)

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.

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
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. 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 WikiProject Gastropods/Categories and 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.
 * 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
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".
 * Terms that are unclear (e.g. "wildlife") should be avoided.
 * Categories that are named for a taxon may contain articles that are not about taxa. For example:
 * Where there is a category for fictional organisms (e.g. Category:Fictional felines) it should be placed under the corresponding category for (real) organisms.
 * A taxon category may contain articles about individual (notable) animals.
 * Category:Important Bird Areas of Europe is placed under Category:Birds of Europe etc (TBC - would it be better recategorized?).
 * 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. 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. -
 * Categories that are under both Category:Genera and Category:Species
 * Categories that are under both prehistoric life and extinctions since 1500
 * 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

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

Appendix A - Levels
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).

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
See discussion at a user talk page