Incertae sedis

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New World vultures, such as the California condor, were placed incertae sedis within the class Aves until the recognition of the new order Cathartiformes. Gymnogyps californianus us fish 3.jpg
New World vultures, such as the California condor, were placed incertae sedis within the class Aves until the recognition of the new order Cathartiformes.
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 incertae sedis. 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
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 incertae sedis.
The Varanopids, a mysterious family of Tetrapods, had controversial relationships with other many land tetrapods. Paleolontologists have mostly assigned them in the past as Eupelycosaurian synapsids. Others have placed them as basal neodiapsids. A compromise is to place them as Amniota incertae sedis. Varanops BW.jpg
The Varanopids, a mysterious family of Tetrapods, had controversial relationships with other many land tetrapods. Paleolontologists have mostly assigned them in the past as Eupelycosaurian synapsids. Others have placed them as basal neodiapsids. A compromise is to place them as Amniota incertae sedis.

Incertae sedis (Latin for 'of uncertain placement') [2] or problematica is a term used for a taxonomic group where its broader relationships are unknown or undefined. [3] Alternatively, such groups are frequently referred to as "enigmatic taxa". [4] 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. [5]

Contents

Examples

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. [12]

Reason for use

Poor description

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: [13]

...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.

Not included in an analysis

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. This is particularly common when 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 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. [5]

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. [5]

Other ways of denoting uncertainty

Uncertain taxonomic assigations of other degrees may be denoted using the 'cf.' (before a taxon name) and '?' (after a taxon name) specifiers. [14]

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". [2] Glossary In botany, a name is not validly published if it is not accepted by the author in the same publication. [12] Article 36.1 In zoology, a name proposed conditionally may be available under certain conditions. [2] Articles 11 and 15 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. [5] 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? album Anton (?Anton)"; the "(?Anton)" indicates the author that assigned the question mark. [5] 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. [5] This practice is not included in the International Code of Zoological Nomenclature, and is used only by paleontologists. [5]

See also

Related Research Articles

Taxonomy (biology) Science of naming, defining and classifying organisms

In biology, taxonomy is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum, class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms.

Genus is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

Subspecies Taxonomic rank subordinate to species

In biological classification, the term subspecies refers to one of two or more populations of a species living in different subdivisions of the species' range and varying from one another by morphological characteristics. A single subspecies cannot be recognized independently: a species is either recognized as having no subspecies at all or at least two, including any that are extinct. The term may be abbreviated to subsp. or ssp. The plural is the same as the singular: subspecies.

Taxon Grouping of biological populations

In biology, a taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is very common, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping.

In botanical nomenclature, variety is a taxonomic rank below that of species and subspecies, but above that of form. As such, it gets a three-part infraspecific name. It is sometimes recommended that the subspecies rank should be used to recognize geographic distinctiveness, whereas the variety rank is appropriate if the taxon is seen throughout the geographic range of the species.

In biology, trinomial nomenclature refers to names for taxa below the rank of species. These names have three parts. The usage is different in zoology and botany.

Type (biology) Specimen(s) to which a scientific name is formally attached

In biology, a type is a particular specimen of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralize the defining features of that particular taxon. In older usage, a type was a taxon rather than a specimen.

Botanical name Scientific name for a plant, alga or fungus

A botanical name is a formal scientific name conforming to the International Code of Nomenclature for algae, fungi, and plants (ICN) and, if it concerns a plant cultigen, the additional cultivar or Group epithets must conform to the International Code of Nomenclature for Cultivated Plants (ICNCP). The code of nomenclature covers "all organisms traditionally treated as algae, fungi, or plants, whether fossil or non-fossil, including blue-green algae (Cyanobacteria), chytrids, oomycetes, slime moulds and photosynthetic protists with their taxonomically related non-photosynthetic groups ."

Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from taxonomy. Plant taxonomy is concerned with grouping and classifying plants; botanical nomenclature then provides names for the results of this process. The starting point for modern botanical nomenclature is Linnaeus' Species Plantarum of 1753. Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN), which replaces the International Code of Botanical Nomenclature (ICBN). Fossil plants are also covered by the code of nomenclature.

Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.

The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.

Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a type, which can be a specimen or a taxon of lower rank, and a description in words. Phylogenetic nomenclature is currently regulated by the International Code of Phylogenetic Nomenclature (PhyloCode).

Form classification Classification of organisms based on their morphology

Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of science is to move "form taxa" to biological taxa whose affinity is known.

São Tomé shorttail Species of bird

The São Tomé shorttail, also known as Bocage's longbill, is a species of passerine bird in the family Motacillidae. It has been classified as the sole member of the genus Amaurocichla, but a 2015 phylogenetic study placed it among the wagtails in the genus Motacilla. It is endemic to the central and southern parts of the island of São Tomé. Its natural habitat is subtropical or tropical moist lowland forests. This species has a small population and is threatened by habitat loss.

Taxonomic rank Level in a taxonomic hierarchy

In biological classification, taxonomic rank is the relative level of a group of organisms in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, order, class, phylum, kingdom, domain, etc.

In biological classification, a species inquirenda is a species of doubtful identity requiring further investigation. The use of the term in English-language biological literature dates back to at least the early nineteenth century.

Open nomenclature is a vocabulary of partly informal terms and signs in which a taxonomist may express remarks about their own material. This is in contrast to synonymy lists, in which a taxonomist may express remarks on the work of others. Commonly such remarks take the form of abbreviated taxonomic expressions in biological classification.

This is a list of terms and symbols used in scientific names for organisms, and in describing the names. For proper parts of the names themselves, see List of Latin and Greek words commonly used in systematic names. Note that many of the abbreviations are used with or without a stop.

Strisores Clade of birds

Strisores is a clade of birds that includes the living families and orders Caprimulgidae, Nyctibiidae (potoos), Steatornithidae (oilbirds), Podargidae (frogmouths), Apodiformes, as well as the Aegotheliformes (owlet-nightjars) whose distinctness was only recently realized. The Apodiformes and the Aegotheliformes form the Daedalornithes.

Algospongia is a class of small, calcified fossil organisms of uncertain taxonomic position, assigned in a comprehensive 2010 review to "Animalia" incertae sedis, but both prior to and post that to an unnamed phylum of Algae; other workers simply list them as Problematica. They occur in carbonate rocks of the Paleozoic era and their last representatives occur in the Late Permian geological period. Characteristic genera include Aoujgalia, Moravammina and the early-appearing Wetheredella, although the taxonomic validity of the last named genus has been disputed.

References

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