binomial nomenclature In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name compos ...

, a ''nomen dubium'' (

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application.

Zoology

In case of a ''nomen dubium'' it may be impossible to determine whether a specimen belongs to that group or not. This may happen if the original type series (i. e.

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

, isotype, syntype or paratype) is lost or destroyed. The zoological and botanical codes allow for a new type specimen, or neotype, to be chosen in this case. A name may also be considered a ''nomen dubium'' if its name-bearing type is fragmentary or lacking important diagnostic features (this is often the case for species known only as fossils). To preserve stability of names, the ''

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...

'' allows a new type specimen, or neotype, to be chosen for a ''nomen dubium'' in this case.

75.5. Replacement of unidentifiable name-bearing type by a neotype. When an author considers that the taxonomic identity of a nominal species-group taxon cannot be determined from its existing name-bearing type (i.e. its name is a ''nomen dubium''), and stability or universality are threatened thereby, the author may request the Commission to set aside under its plenary power rt. 81the existing name-bearing type and designate a neotype.

For example, the crocodile-like

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avia ...

ian reptile ''Parasuchus hislopi''

Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...

, 1885 was described based on a

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

ry rostrum (part of the snout), but this is no longer sufficient to distinguish ''

Parasuchus ''Parasuchus'' is an extinct genus of basal phytosaur known from the Late Triassic (late Carnian to early Norian stage) of Andhra Pradesh and Madhya Pradesh, India. At its most restricted definition, ''Parasuchus'' contains a single specie ...

'' from its close relatives. This made the name ''Parasuchus hislopi'' a ''nomen dubium''. In 2001 a paleontologist proposed that a new type specimen, a complete skeleton, be designated. The International Commission on Zoological Nomenclature considered the case and agreed in 2003 to replace the original type specimen with the proposed neotype.

Bacteriology

In bacteriological nomenclature, ''nomina dubia'' may be placed on the list of rejected names by the Judicial Commission. The meaning of these names is uncertain. Other categories of names that may be treated in this way (rule 56a) are: *ambiguous names, ''nomina ambigua'', have been used with more than one meaning *names causing confusion, ''nomina confusa'', are based on a mixed culture *perplexing names, ''nomina perplexa'', confusingly similar names *perilous names, ''nomina periculosa'', names that may lead to accidents endangering life or health or with potential serious economic consequences

Botany

In botanical nomenclature the phrase ''nomen dubium'' has no status, although it is informally used for names whose application has become confusing. In this regard, its synonym '' nomen ambiguum'' is of more frequent use. Such names may be proposed for rejection.

References

{{Use dmy dates, date=October 2018 Zoological nomenclature Latin biological phrases

Zoology

Bacteriology

Botany

See also

References