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Nomen dubium

Nomen dubium is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nomen dubium rather than just read about it. In short: In binomial nomenclature, a nomen dubium (Latin 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.

Nomen dubium — main illustration
Nomen dubium — illustration

Key takeaways

  • Nomen dubium belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Nomen dubium to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Nomen dubium from memory before moving on to harder problems.

Reference excerpt

In binomial nomenclature, a nomen dubium (Latin 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, 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 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 [Art. 81] the existing name-bearing type and designate a neotype. For example, the crocodile-like archosaurian reptile Parasuchus hislopi Lydekker, 1885 was described based on a premaxillary rostrum (part of the snout), but this is no longer sufficient to distinguish Parasuchus 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.

See also Glossary of scientific naming Species inquirenda, a species of doubtful identity requiring further investigation Nomen nudum, a name proposed with no description (or illustration) Nomen oblitum, an obsolete name

References

Illustrations

Nomen dubium: Gadus callarias, an example of nomen dubium, now considered a potential synonym or a subspecies of G. morhua
Gadus callarias, an example of nomen dubium, now considered a potential synonym or a subspecies of G. morhua
Nomen dubium: Preserved specimen of Tritonellium barthi Valenciennes, 1858 (nomen dubium)
Preserved specimen of Tritonellium barthi Valenciennes, 1858 (nomen dubium)

Worked examples

Example 1 — a first encounter with Nomen dubium

Start with the simplest possible case. Write down what Nomen dubium claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nomen dubium before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nomen dubium ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nomen dubium

In research
Nomen dubium appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Nomen dubium in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Nomen dubium is common in secondary-school and first-year university syllabi. It links to neighbouring topics Latin biological phrases, Nomina dubia, Zoological nomenclature, so understanding it makes those chapters shorter.
In everyday life
Look for Nomen dubium outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nomen dubium in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Nomen dubium means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Nomen dubium out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nomen dubium in simple terms?

In binomial nomenclature, a nomen dubium (Latin 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.

Why does Nomen dubium matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nomen dubium?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nomen dubium.

Tags

  • Latin biological phrases
  • Nomina dubia
  • Zoological nomenclature

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