The VendozoanCharnia. The actual nature or phylogeny of the Vendozoan is not known, leading to form taxa only
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.[1]
Form taxonomy is restricted to fossils that preserve too few characters for a conclusive taxonomic definition or assessment of their biological affinity, but whose study is made easier if a binomial name is available by which to identify them.[2] The term "form classification" is preferred to "form taxonomy"; taxonomy suggests that the classification implies a biological affinity, whereas form classification is about giving a name to a group of morphologically-similar organisms that may not be related.[1]
A "parataxon" (not to be confused with parataxonomy), or "sciotaxon" (Gr. "shadow taxon"), is a classification based on incomplete data: for instance, the larval stage of an organism that cannot be matched up with an adult. It reflects a paucity of data that makes biological classification impossible.[1] A sciotaxon is defined as a taxon thought to be equivalent to a true taxon (orthotaxon), but whose identity cannot be established because the two candidate taxa are preserved in different ways and thus cannot be compared directly.[1]
Examples
In zoology
Form taxa are groupings that are based on common overall forms. Early attempts at classification of labyrinthodonts was based on skull shape (the heavily armoured skulls often being the only preserved part). The amount of convergent evolution in the many groups led to a number of polyphyletic taxa.[3] Such groups are united by a common mode of life, often one that is generalist, in consequence acquiring generally similar body shapes by convergent evolution. Ediacaran biota — whether they are the precursors of the Cambrian explosion of the fossil record, or are unrelated to any modern phylum — can currently only be grouped in "form taxa". Other examples include the seabirds and the "Graculavidae". The latter were initially described as the earliest family of Neornithes but are nowadays recognized to unite a number of unrelated early neornithine lineages, several of which probably later gave rise to the "seabird" form taxon of today.
Fossil eggs are classified according to the parataxonomic system called Veterovata. There are three broad categories in the scheme, on the pattern of organismal phylogenetic classification, called oofamilies, oogenera and oospecies (collectively known as ootaxa). The names of oogenera and oofamilies conventionally contain the root "oolithus" meaning "stone egg", but this rule is not always followed. They are divided up into several basic types: Testudoid, Geckoid, Crocodiloid, Dinosauroid-spherulitic, Dinosauroid-prismatic, and Ornithoid.[4]
In paleobotany, two terms were formerly used in the codes of nomenclature, "form genera" and "organ genera", to mean groups of fossils of a particular part of a plant, such as a leaf or seed, whose parent plant is not known because the fossils were preserved unattached to the parent plant.[5][6] A later term "morphotaxa" also allows for differences in preservational state. These three terms have been replaced as of 2011 by provisions for "fossil-taxa" that are more similar to the provisions for other types of plants.[7][8]
Names given to organ genera could only be applied to the organs in question, and could not be extended to the entire organism.[2] Fossil-taxon names can cover several parts of an organism, or several preservational states, but do not compete for priority with any names for the same organism that are based on a non-fossil type.[7]
The part of the plant was often, but not universally, indicated by the use of a suffix in the generic name:
wood fossils may have generic names ending in -xylon
leaf fossils generic names ending in -phyllum
fruit fossils generic names ending in -carpon, -carpum or -carpus
pollen fossils generic names ending in -pollis or -pollenoides.
1 2 Turland, N. (2013), "The Code Decoded: A user's guide to the International Code of Nomenclature for algae, fungi, and plants", Regnum Vegetabile, vol.155, Koeltz Scientific Books, ISBN978-3-87429-433-1
In biological classification, a subfamily is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zoological subfamily names with "-inae".
In biology, a tribe is a taxonomic rank above genus, but below family and subfamily. It is sometimes subdivided into subtribes. By convention, all taxa ranked above species are capitalized, including both tribe and subtribe.
In botanical nomenclature, a form is one of the "secondary" taxonomic ranks, below that of variety, which in turn is below that of species; it is an infraspecific taxon. If more than three ranks are listed in describing a taxon, the "classification" is being specified, but only three parts make up the "name" of the taxon: a genus name, a specific epithet, and an infraspecific epithet.
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Incertae sedis or problematica is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty at specific taxonomic levels is indicated by incertae familiae, incerti subordinis, incerti ordinis and similar terms.
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 ."
In taxonomy, a nomen nudum is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate description. This makes it a "bare" or "naked" name, which cannot be accepted as it stands. A largely equivalent but much less frequently used term is nomen tantum. Sometimes, "nomina nuda" is erroneously considered a synonym for the term "unavailable names". However, not all unavailable names are nomina nuda which applies to published names, i.e. any published name that does not fulfill the requirements of Article 12 or Article 13.
In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants.
Nomenclature codes or codes of nomenclature are the various rulebooks that govern the naming of living organisms. Standardizing the scientific names of biological organisms allows researchers to discuss findings.
In botany, the correct name according to the International Code of Nomenclature for algae, fungi, and plants (ICN) is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, position and rank. Determining whether a name is correct is a complex procedure. The name must be validly published, a process which is defined in no less than 16 Articles of the ICN. It must also be "legitimate", which imposes some further requirements. If there are two or more legitimate names for the same taxon, then the correct name is the one which has priority, i.e. it was published earliest, although names may be conserved if they have been very widely used. Validly published names other than the correct name are called synonyms. Since taxonomists may disagree as to the circumscription, position or rank of a taxon, there can be more than one correct name for a particular plant. These may also be called synonyms.
In botany, a section is a taxonomic rank below the genus, but above the species. The subgenus, if present, is higher than the section, and the rank of series, if present, is below the section. Sections may in turn be divided into subsections.
In botanical nomenclature, a hybrid may be given a hybrid name, which is a special kind of botanical name, but there is no requirement that a hybrid name should be created for plants that are believed to be of hybrid origin. The International Code of Nomenclature for algae, fungi, and plants (ICNafp) provides the following options in dealing with a hybrid:
In zoological nomenclature, the valid name of a taxon is the correct scientific name for that taxon. The valid name must be used for that taxon, regardless of any other name that may currently be used for that taxon, or may previously have been used. A name can only be valid when it is an available name under the International Code of Zoological Nomenclature (ICZN); if a name is unavailable, then it cannot be considered either valid or invalid.
In botany, the phrase ordo naturalis, 'natural order', was once used for what today is a family. Its origins lie with Carl Linnaeus who used the phrase when he referred to natural groups of plants in his lesser-known work, particularly Philosophia Botanica. In his more famous works the Systema Naturae and the Species Plantarum, plants were arranged according to his artificial "Sexual system", and Linnaeus used the word ordo for an artificial unit. In those works, only genera and species were "real" taxa.
In botanical nomenclature, autonyms are automatically created names, as regulated by the International Code of Nomenclature for algae, fungi, and plants that are created for certain subdivisions of genera and species, those that include the type of the genus or species. An autonym might not be mentioned in the publication that creates it as a side-effect. Autonyms "repeat unaltered" the genus name or species epithet of the taxon being subdivided, and no other name for that same subdivision is validly published. For example, Rubus subgenus Eubatus is not validly published, and the subgenus is known as Rubus subgen. Rubus.
In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype. Often there is more than one paratype. Paratypes are usually held in museum research collections.
Priority is a principle in biological taxonomy by which a valid scientific name is established based on the oldest available name. It is a decisive rule in botanical and zoological nomenclature to recognise the first binomial name given to an organism as the correct and acceptable name. The purpose is to select one scientific name as a stable one out of two or more alternate names that often exist for a single species.
In biological nomenclature, the principle of typification is one of the guiding principles.
An isonym, in botanical taxonomy, is a name of a taxon that is identical to another designation, and based on the same type, but published at a different time by different authors. Citation from that source follows:
When the same name, based on the same type, has been published independently at different times by different authors, then only the earliest of these "isonyms" has nomenclatural status. The name is always to be cited from its original place of valid publication, and later isonyms may be disregarded.
Dendriscocaulon is a taxonomic name that has been used for a genus of fruticose lichen with a cyanobacteria as the photobiont partner of the fungus. Dendriscocaulon is considered a taxonomic synonym of the genus Sticta, a foliose lichen, which generally has a green alga as the photobiont partner. Lichens that have been called Dendriscocaulon or Sticta involve the same fungal species. They show dramatically different morphology, may grow side-by-side, and mixed forms exist where different algae are growing within different portions of the same fungal thallus. The biochemistry of the two forms is very different, but the DNA sequences from the fungus and the photobiont can be distinguished using different primers for DNA sequencing.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
