What is a type specimen?

How to name a species

Naming a species is one of the most important decisions that a scientist might make during their career, as this name could be attached to that group of organisms or minerals for the rest of time. While people have been naming species for many centuries, the modern naming system began with Swedish scientist Carl Linnaeus in the 1700s.

Every species is given a two-part scientific name, also known as a binomial. Take the blue whale, for example, which has the scientific name Balaenoptera musculus. In scientific texts, the surname of the scientist who named the species is normally listed afterwards – in this case, it would be Balaenoptera musculus Linnaeus.

The genus and species names are sometimes the same, such as Puffinus puffinus for the manx shearwater. This is known as a tautonymous name, or tautonym.

Together, the different parts of the name help scientists to understand a species and its taxonomy. The first part of the name is the genus name – it refers to the group of close relatives the whale belongs to. The second part of the name is the species name – it identifies its species. Finally, the name of the scientist helps future researchers to find the scientific text the species was first named in.

In most cases, scientists will be adding a species to an existing genus and so they only need to come up with the second part of the name. Occasionally, however, they might name an organism that’s so different from any other that they create a new genus as well.

Choosing what these names are is a matter of personal preference. Our wasp expert Dr Gavin Broad has named many species in his career. He says that “the best names are those that say something about an organism”.

“One option is to name an animal after a memorable characteristic,” explains Gavin. “For example, I helped to name a wasp with a distinctive dot and dash pattern Xanthopimpla morsei after Morse code.”

“Other people name species after the place they were found, though this can get tricky when there are multiple species from the same area. There are ways of getting around this, and I once named a wasp after Napoleon Bonaparte to reference that it was found on St Helena, the island he was exiled to.”

Gavin’s not alone in naming species after people – many scientists have chosen to honour fellow researchers or politicians and other public figures. Species named after celebrities and popular culture have become more common recently, with Beyoncé, Pokémon and Kermit the Frog among those being honoured.

Some of these names highlight a similarity between a species and its namesake, such as the muscular appearances of the actor Arnold Schwarzenegger and the beetle Agra schwarzeneggeri. Other names, meanwhile, help to raise awareness of threatened or overlooked parts of the tree of life.

The insect genus Polychisme, meanwhile, hides a secret message from scientist George Willis Kirkaldy. He’s believed to have named Polychisme – pronounced Polly kiss me – as a reference to a former partner.

The rules of species naming

While species names can be inspired by almost anything, scientists have to follow certain rules. These are laid out in the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICN) for other types of life.

These naming systems only apply to scientific binomial names, ensuring that the names used by scientists are consistent all across the world. They don’t apply to the common names used for organisms in everyday conversations, such as blackbird, though there are some organisations that try to regulate these.

The scientific codes are long and complex but Dr Jeff Streicher, our Senior Curator in Charge of Amphibians and Reptiles, explains that they rely on a few basic principles that a scientist must follow for their name to become official.

“The main step is a description,” Jeff says. “This can go into detail about what a species looks like and how it differs from its close relatives.”

“The description must identify at least one specimen to represent the species, but otherwise there aren’t any specific rules about what it needs to include. So, some scientists might include genetic or behavioural data and others won’t.”

“The description then needs to be published in a publicly accessible journal or data repository so that other scientists can read it for themselves.”

The rules also follow a principle known as priority. Generally, this means that the first name for a species that follows all the rules of the code becomes its official name. Any new name for the same species published afterwards becomes a synonym of the first and isn’t used again.

The names of a species might change afterwards, but only in certain circumstances. For example, if new research shows that a particular population is different enough from the rest of its species, then it may be named as a new species in its own right. In this case, a name previously thought of as a synonym might become the new species’ official name.

The names of historic species, meanwhile, can be suppressed if a later name has become more common. For example, the first known bones of Tyrannosaurus rex were originally named Manospondylus gigas, but because this name was never widely used it’s now been dropped to avoid confusion.

Some scientists have also called for names to be changed because they are offensive or honour someone inappropriate. In 2024, botanists voted to change the name of more than 300 plants, fungi and algae containing the words ‘caffra’ or ‘cafra’ because they’re derived from a racist slur.

The ICN was also changed so that newly suggested names can be vetted by a panel of scientists to ensure they aren’t derogatory. Neither the ICN and ICZN, however, have established a process to allow historic names to be altered more generally – though this might change in the future.

What is a holotype?

A holotype is the individual specimen to which the name of a species is attached. It acts as a permanent physical reference for the name, and scientists can find out if something they have found is a member of a species by comparing its features to the holotype.

While it’s up to the scientists naming species to define holotypes, they should try to choose the individual that’s most representative of a species.

“When a species has a broad range of variation, the holotype needs to be the most typical,” explains Gavin. “It needs to be in good condition, if possible, because missing or damaged body parts will make it more difficult to identify other members of its species.”

“The holotype also needs good locality data, clear features and a date of collection to help find the species in the wild in the future.”

What makes something a good holotype can depend on the different groups. In moths, for example, it’s best to designate a male holotype because their genitals are easier to distinguish between species. In wasps, on the other hand, females tend to have more observable characteristics.

Dr Gemma Bramley, a taxonomist from Royal Botanic Gardens, Kew, says that it’s more complicated for plants. In botany, for example, illustrations can be used as the holotype of historic species and may be used for new species in certain circumstances.

It’s also possible for historic animal species to be represented by illustrations as is the case for the African rail.

Botanists are also more able to collect multiple specimens of the same plant at the same time than scientists studying animals. If one of these specimens is later made a holotype of a new species, the rest become duplicates of the holotype known as isotypes.

It’s up to the botanist naming a species to decide which specimen becomes the holotype, but it’s usually best to pick a specimen with flowers or fruits.

“Flowers and fruits are typically the most informative parts of the plant when it comes to taxonomy,” Gemma adds. “Species are often identified based on the differences in these features, so they should be on show in the holotype.”

Holotypes don’t all have to be biological specimens either. Minerals also have species, whose names are given by geologists using the rules of the Commission on New Minerals, Nomenclature and Classification.

The fossils of extinct animals, plants and other organisms can also be used as type specimens to name species when enough of them survives. Fossilised traces of animals, such as burrows or footprints, are also used as type specimens in the naming of species by scientists.

Once a holotype has been chosen, it then needs to be placed somewhere that other scientists can easily access it. Holotypes are generally kept in museums, herbaria and other public collections where they’ll be preserved, hopefully forever.

This means they’re always available to be examined by scientists, no matter how much time has passed. For example, the holotype of the large-billed reed warbler, Acrocephalus orinus, was placed in our care in 1867. It was used to rediscover the species in 2006 when living warblers were found in Thailand.

What is a type specimen?

Type specimens are any specimens that are associated with the name of a species or subspecies. While holotypes are the most important of these, they aren’t always enough to help identify a species on their own. In this case, scientists may use other kinds of type specimens.

For example, paratypes are specimens used in a description that aren’t the holotype or any of the isotypes. They’re usually important in showing the full range of variation in a species and highlight features that can’t be seen in a holotype or isotype.

In animals this can include an allotype, which is a specimen of the opposite sex from the holotype. It’s often used when species are sexually dimorphic, meaning that males and females look different, so that all individuals can be identified.

“Sometimes, a holotype can be enough to represent a species’ diversity on its own,” Jeff explains. “In most cases, however, variation within species means that a single individual cannot represent all of its diversity.”

“This means that, where possible, a species should be named from as many individuals as needed to show what makes a species unique.”

Gemma adds that, when collecting plants, it’s a good idea to make duplicate specimens and distribute them to different institutions where permits allow.

“International partnerships are at the heart of botanical research, so it’s important to share access to collections and the data they represent,” she explains. “Generally, this will mean the most important specimens are housed in the country of origin and the others will be distributed to leading herbaria within that country and around the world.”

This system of holotypes and paratypes is relatively recent, however, and only started in the mid-twentieth century. Many species before then were instead described from a group of different specimens, known as syntypes, that jointly bear the name of a species.

While it might not be standard scientific practice today, these syntypes are still the basis for globally common species such as woodlice. Despite their age, they’re just as important to scientists now as they were hundreds of years ago.

“Early species descriptions are generally only about a paragraph long and don’t go into too much detail,” Jeff says. “This makes historic types very important, as one person’s idea of a species can be very different from another’s. They cover a lot of diversity that these descriptions don’t go into.”

Syntypes can, however, sometimes cause confusion about a species. For example, they might include individuals of completely different ages or colour morphs, which can make it difficult for other scientists to identify a species. It’s particularly confusing if some of the syntypes are later identified as being part of a different species altogether.

To avoid confusion, it can be useful to choose the most representative syntype to be the lectotype. This becomes the name-bearing representative of the species, similar to a holotype, while all the former syntypes becomes paralectotypes.

The remains of Carl Linnaeus, for example, were named in the 1950s as the lectotype of our species Homo sapiens.

Type specimens can also be named for higher taxonomic ranks than species. The type species, for example, is the sole representative of a genus while the type genus is the name-bearer for a family.

What happens if a type specimen is missing?

Occasionally, a scientist might go looking for the type specimens of a species and come away empty handed. This is generally an issue with historic type specimens that weren’t placed in a public collection, as they might have been lost since being named.

These type specimens can sometimes be rediscovered by carefully tracing where they’ve been over the past few centuries. But in other cases, the type specimens might be lost forever. Many type specimens were destroyed during World War II, such as the holotype of the dinosaur Spinosaurus aegyptiacus.

In this case, scientists can name a neotype if the loss of the holotype makes it hard to identify a species. This becomes the new name-bearing type of the species while the holotype is lost and can be replaced by the original if it’s ever rediscovered.

If possible, it’s chosen from the original material – the specimens used by a scientist to describe the original species. If there aren’t any of these, then specimens collected from the same area of the original type are often used instead.

“Without types, the rules of taxonomy are difficult to enforce,” explains Jeff. “Science has to be repeatable, and type specimens provide an empirical basis for what a species is. So, if a holotype is lost, it’s important to replace it with a neotype.”

Replacements for the holotype can sometimes be chosen even if it still exists, usually because the holotype isn’t a useful reflection of the species it describes. The replacement is still known as a neotype by the ICZN, while the ICN calls it an epitype instead.

For example, the holotype of the bird-like dinosaur Archaeopteryx lithographica was originally the impression of feather, but this couldn’t be identified to any one species. So, in 2011, the ICZN voted to choose the more complete London Archaeopteryx, which we look after, as the neotype for the species.

Whether they’re recently chosen neotypes or ancient holotypes, every type specimen is vital to understanding species. They’re the foundation of how we understand nature and catalogue Earth’s extraordinary biodiversity.