Guide to tautonyms, triple tautonyms, and binomial nomenclature

A tautonym is an interesting quirk in the naming system of animals, where the words used for the genus and specific names are identical. Learn more about tautonyms, triple tautonyms, binomial nomenclature, and examples of tautonyms.

A female spotted hyena with her young cub standing on top of her, Khwai River, Botswana. © Jami Tarris/Getty

What is a tautonym?

A tautonym is when the scientific name for a species is identical for both the genus and the specific names. Whilst this is relatively common in zoology (animals), in botany (plants) it is not allowed. However, differences of just one letter are allowed in botany.

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Are there any triple tautonyms?

Triple tautonyms can also occur when the scientific name of a subspecies, which is part of a species with an existing tautonym, has the same word used again.

What is a scientific name?

The scientific name of a species is assigned by scientists studying it, and is usually based on Latin or Greek words. Each scientific name consists of two words, the genus and the specific name, which is known as binomial nomenclature.

For example, the scientific name of the common bottlenose dolphin is Tursiops truncatus, where ‘Tursiops’ is the genus name and is capitalised and ‘truncatus’ is the specific name and is in lower case.

When writing out scientific names, the genus is always capitalised and the species is always lower case. Both should always be written in italics (or underlined if italics are unsuitable).

There are internationally agreed codes for applying scientific names, overseen by the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICNafp).

When writing out scientific names, they should be written in full the first time and can then be abbreviated with a full stop when referred to afterwards. For example, having referred to the common bottlenose dolphin previously in this article, any further use of its scientific name would be written as T. truncatus.

In the case of subspecies, an additional subspecies name is added to the scientific name, for example there are two subspecies of mountain zebra: Cape mountain zebra (Equus zebra zebra), and Hartmann’s mountain zebra (E. z. hartmannae).

The Cape mountain zebra is a subspecies of the mountain zebra. © Hoberman Collection/Universal Images Group/Getty
The Cape mountain zebra is a subspecies of the mountain zebra. © Hoberman Collection/Universal Images Group/Getty

Sometimes the scientific name for a species may change, when scientists decide that a species actually belongs in a different genus. Usually the specific name of the species will remain the same, however it may need to be changed if there is another species in that genus with the same specific name.

Scientific names enable scientists and naturalists to check whether they are talking about the same species. This is useful for when a species may have multiple common names in a language, such as the greater skua (Stercorarius skua) which is also known as a bonxie in Shetland. It is also useful for when scientists from different countries are discussing wildlife.

Some species do not have common names, and are only known by their scientific names.

Scientific names can become part of common speech, with famous examples including Tyrannosaurus rex (sometimes referred to as T. rex) and Boa constrictor. Many gardeners are familiar with using scientific names, such as Agapanthus and Chrysanthemum. As such, it is common to find these words not written in italics.

What is a species?

The concept of a species is arguably the most fundamental in biology. It is surprising, then, that it has caused scientists so much head-scratching. Charles Darwin wanted to do away with the concept altogether, considering it to be defining the indefinable.

The most used definition centres on interbreeding, stating that a species is a group within which two individuals can breed to produce fertile offspring.

In general, this definition holds water, but it can lead to surprising groupings. For example, due to climate change, polar bears and grizzly bears have been coming into contact and producing fertile young. Should we consider these bears one species?

Grizzlies have produced fertile young with polar bears, but are they the same species? © Laura Hedien/Getty
Grizzlies have produced fertile young with polar bears, but are they the same species? © Laura Hedien/Getty

The focus on sex also leaves out organisms that reproduce asexually. Other definitions consider ancestry, though where the lines should be drawn is unclear – are we the same species as our water-dwelling ancestors? Further definitions focus on ecology, geography and physiology.

This Q&A originally appeared in BBC Wildlife Magazine, and was answered by Leoma Williams.

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Insects

Anthrax fly (Anthrax anthrax)

Anthrax fly on a bee hotel. © Getty
Anthrax fly on a bee hotel. © Getty

Goat moth (Cossus cossus)

A goat moth freshly emerged from its pupal case. © Jasius/Getty
A goat moth freshly emerged from its pupal case. © Jasius/Getty

Other invertebrates

By-the-wind sailor (Velella vellela)

Large number of by-the-wind-sailors washed up on Long Beach, near Tofino, on Vancouver Island, Canada. © James R.D. Scott/Getty
Large number of by-the-wind-sailors washed up on Long Beach, near Tofino, on Vancouver Island, Canada. © James R.D. Scott/Getty

Fish

Short-snouted seahorse (Hippocampus hippocampus)

Short-snouted seahorse, in the Black Sea, Crimea, Ukraine. © Andrey Nekrasov/Getty
Short-snouted seahorse, in the Black Sea, Crimea, Ukraine. © Andrey Nekrasov/Getty

European eel (Anguilla anguilla)

A European eel in Mediterranean Sea in Antalya, Turkey. © Tahsin Ceylan/Anadolu Agency/Getty
A European eel in Mediterranean Sea in Antalya, Turkey. © Tahsin Ceylan/Anadolu Agency/Getty

Amphibians

European toad (Bufo bufo), also known as common toad

Common toad in Devon, UK. © Mike Hill/Getty
Common toad in Devon, UK. © Mike Hill/Getty

Reptiles

Green iguana (Iguana iguana)

Green iguana in Corcovado National Park, Costa Rica. © Bas Vermolen/Getty
Green iguana in Corcovado National Park, Costa Rica. © Bas Vermolen/Getty

Birds

Chough (Pyrrhocorax pyrrhocorax)

A chough in Wales, UK. © Sandra Standbridge/Getty
A chough in Wales, UK. © Sandra Standbridge/Getty

Black-tailed godwit (Limosa limosa)

A flock of black-tailed godwits in flight, Ouse Washes, Norfolk, UK. © Mike Powles/Getty
A flock of black-tailed godwits in flight, Ouse Washes, Norfolk, UK. © Mike Powles/Getty

Shelduck (Tadorna tadorna)

A male shelduck swimming in Norfolk, UK. © Mike Powles/Getty
A male shelduck swimming in Norfolk, UK. © Mike Powles/Getty

European goldfinch (Carduelis carduelis)

Goldfinch perching on cherry tree branch. © Lauren Tucker/Getty
Goldfinch perching on cherry tree branch. © Lauren Tucker/Getty

Red kite (Milvus milvus)

Red kite flying in mid Wales. © Steve Littlewood/Getty
Red kite flying in mid Wales. © Steve Littlewood/Getty

Whooper swan (Cygnus cygnus)

A whooper swan in flight at Caerlaverock, Scotland. © Education Images/Getty
A whooper swan in flight at Caerlaverock, Scotland. © Education Images/Getty

Eurasian magpie (Pica pica)

With its pied colouring, the Eurasian magpie is easy to identify. © Garden Picture Library/Getty
With its pied colouring, the Eurasian magpie is easy to identify. © Garden Picture Library/Getty

Little auk (Alle alle)

Hundreds of starling-sized auks can be seen along the Scottish coast. © Getty
Hundreds of starling-sized auks can be seen along the Scottish coast. © Getty

Eurasian crane (Grus grus), also known as common crane

A female common crane at the nest with a one day old chick, in Norfolk, UK. © Mike Powles/Getty
A female common crane at the nest with a one day old chick, in Norfolk, UK. © Mike Powles/Getty

Goldcrest (Regulus regulus)

A goldcrest perched on a bramble looking for insects. © Gary Chalker/Getty
A goldcrest perched on a bramble looking for insects. © Gary Chalker/Getty

Mammals

Lowland gorilla (Gorilla gorilla)

  • Triple tautonym: Western lowland gorilla (G. g. gorilla)
Western lowland gorilla dominant male silverback 'Makumba' aged 32 years, in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. © Fiona Rogers/Getty
Western lowland gorilla dominant male silverback ‘Makumba’ aged 32 years, in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. © Fiona Rogers/Getty

Eurasian badger (Meles meles)

European badger cub in Ashdown Forest, Sussex, England. © James Warwick/Getty
European badger cub in Ashdown Forest, Sussex, England. © James Warwick/Getty

Spotted hyena (Crocuta crocuta)

A female spotted hyena with her young cub standing on top of her, Khwai River, Botswana. © Jami Tarris/Getty
A female spotted hyena with her young cub standing on top of her, Khwai River, Botswana. © Jami Tarris/Getty

Pine marten (Martes martes)

A pine marten standing on a mossy mound in the Highlands of Scotland, UK. © Sandra Standbridge/Getty
A pine marten standing on a mossy mound in the Highlands of Scotland, UK. © Sandra Standbridge/Getty

Red fox (Vulpes vulpes)

Red fox at the edge of Ashdown Forest, Sussex, England, UK. © James Warwick/Getty
Red fox at the edge of Ashdown Forest, Sussex, England, UK. © James Warwick/Getty

Fallow deer (Dama dama)

A male fallow deer (buck) and a female (doe). © Alan Tunnicliffe Photography/Getty
A male fallow deer (buck) and a female (doe). © Alan Tunnicliffe Photography/Getty

Roe deer (Capreolus capreolus)

A male (buck) roe deer among wildflowers on the Rudge Hill Nature Reserve, The Cotswolds, Gloucestershire, UK. © Peter Llewellyn/Getty
A male (buck) roe deer among wildflowers on the Rudge Hill Nature Reserve, The Cotswolds, Gloucestershire, UK. © Peter Llewellyn/Getty

Eurasian lynx (Lynx lynx)

Eurasian lynx (in mainland Europe) hunting during winter. © Arterra/UIG/Getty
Eurasian lynx (in mainland Europe) hunting during winter. © Arterra/UIG/Getty

Edible dormouse (Glis glis), also known as fat dormouse

An edible dormouse, in Italy. © Getty
An edible dormouse, in Italy. © Getty