Incertae sedis

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Incertae sedis (Latin for 'of uncertain placement') or problematica are terms used for a taxonomic group where its broader relationships are unknown or undefined. Incertae sedis_sentence_0

Alternatively, such groups are frequently referred to as "enigmatic taxa". Incertae sedis_sentence_1

In the system of open nomenclature, uncertainty at specific taxonomic levels is indicated by incertae familiae (of uncertain family), incerti subordinis (of uncertain suborder), incerti ordinis (of uncertain order) and similar terms. Incertae sedis_sentence_2

Examples Incertae sedis_section_0

Incertae sedis_unordered_list_0

  • The fossil plant Paradinandra suecica could not be assigned to any family, but was placed incertae sedis within the order Ericales when described in 2001.Incertae sedis_item_0_0
  • The fossil Gluteus minimus, described in 1975, could not be assigned to any known animal phylum. The genus is therefore incertae sedis within the kingdom Animalia.Incertae sedis_item_0_1
  • While it was unclear to which order the New World vultures (family Cathartidae) should be assigned, they were placed in Aves incertae sedis. It was later agreed to place them in a separate order, Cathartiformes.Incertae sedis_item_0_2
  • Bocage's longbill, Motacilla bocagii, previously known as Amaurocichla bocagii, is a species of 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.Incertae sedis_item_0_3

In formal nomenclature Incertae sedis_section_1

When formally naming a taxon, uncertainty about its taxonomic classification can be problematic. Incertae sedis_sentence_3

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. Incertae sedis_sentence_4

Reason for use Incertae sedis_section_2

Poor description Incertae sedis_section_3

This excerpt from a 2007 scientific paper about crustaceans of the Kuril-Kamchatka Trench and the Japan Trench describes typical circumstances through which this category is applied in discussing: Incertae sedis_sentence_5

Not included in an analysis Incertae sedis_section_4

If a formal 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. Incertae sedis_sentence_6

This is particularly common when molecular phylogenies are generated, since tissue for many rare organisms is hard to obtain. Incertae sedis_sentence_7

It is also a common scenario when fossil taxa are included, since many fossils are defined based on partial information. Incertae sedis_sentence_8

For example, if the phylogeny was constructed using soft tissue and vertebrae as principal characters and the taxon in question is only known from a single tooth, it would be necessary to label it incertae sedis. Incertae sedis_sentence_9

Controversy Incertae sedis_section_5

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. Incertae sedis_sentence_10

In zoological nomenclature Incertae sedis_section_6

In botany, a name is not validly published if it is not accepted by the author in the same publication. Incertae sedis_sentence_11

In zoology, a name proposed conditionally may be available under certain conditions. Incertae sedis_sentence_12

For uncertainties at lower levels, the system of open nomenclature suggests that question marks be used to denote a questionable assignment. Incertae sedis_sentence_13

For example, if a new species was given the specific epithet album by Anton and attributed with uncertainty to Agenus, it could be denoted "Agenus? Incertae sedis_sentence_14

album Anton (?Anton)"; the "(?Anton)" indicates the author that assigned the question mark. Incertae sedis_sentence_15

So if Anton described Agenus album, and Bruno called the assignment into doubt, this could be denoted "Agenus? Incertae sedis_sentence_16

album (Anton) (?Bruno)", with the parentheses around Anton because the original assignment (to Agenus) was modified (to Agenus?) Incertae sedis_sentence_17

by Bruno. Incertae sedis_sentence_18

See also Incertae sedis_section_7

Incertae sedis_unordered_list_1

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: sedis.