How to Write Scientific Names of Animals

Introduction

Scientific names must be printed or written in certain ways to reduce misunderstandings among scientists working in different countries, subdisciplines or time periods. The many rules seem very picky to lay people, but as biologists and zoologists, you must learn to write and use scientific names properly and understand at least some of the jargon of biological nomenclature.

In ZO 150, points are deducted from lab practical answers, discussion question answers, and genus reports if names are not printed or written and used correctly. Refer to this short guide every time you come across a scientific name in lecture notes or the text, and see how the rules are applied in those examples until you learn to use them properly yourself. Correct your notes, labels of drawings, etc. as necessary when you do them, rather than allowing bad habits to develop.

Scientific Names

Official, scientific names are designated for each taxon (the plural is taxa) of animals, just as they are for all living organisms.

A taxon is a group of organisms defined by particular reproductive, anatomical, or genetically determined similarities.
Each taxon is named. Names are almost always unique, but sometimes the same name will be used inadvertently for both plant and animal orders, or for two, very distantly related animal families.

Taxonomic names are arranged into a hierarchy with an indefinite number of levels.

The basic taxonomic levels are domain, kingdom, phylum, class, order, family and species binomial (genus + specific epithet).

Intermediate levels are indicated by a wide variety of prefixes.

Examples: subkingdom, subphylum, infraclass, superfamily.
Some hierarchies include a level between sub- or infra-family and genus, called "tribe."

Scientific names for taxonomic levels above genus are always capitalized but not italicized (nor underlined when handwritten).

Example: the scientific order name of lemurs, monkeys, apes and humans, Primates

The scientific name for a taxon of organisms is exactly the same in all languages and places.

Common Names

Common names are not officially defined, and the common name of a single species of animal may differ between languages, regions, or even ethnic groups of people in a single community. Also, many animals in different species may share the same common name.

Common names are generally not capitalized (except as required grammatically).

Examples: tiger shark, timber wolf, daisy, puffball fungus

Scientific names are often "anglicized" by changing their endings to English format. Anglicized names are treated as common names and should not be capitalized.

Examples: Chordata becomes chordates, Hominidae becomes hominids, Eukarya becomes eukaryotes

Exception: parts of the common names for some animals are capitalized because they are based on a place or person's name.

Examples: Kirtland's warbler, Carolina wren

In rare cases, the scientific name for genus and the common name for an organism are the same.

Example: hydra, Hydra

When one of these identical-common-name-genus-name cases is intended to apply to a particular genus, it should be capitalized and italicized.

But when it is referring to a less specifically identified animal with a body form that might belong to any of several particular genera, it should be written lower case and not italicized

Example: animals with a hydra-like body form may be in any of these genera Hydra, Chlorohydra or Pelmatohydra. When the particular genus is not identified, the name should be written lower case and not italicized -- hydra.

Species Names

The term species (plural: species) in proper scientific usage means a defined taxon of organisms within a particular genus.

A species includes all individuals, and only those individuals, that are capable of interbreeding.

More exactly, there should be at least a small probability that the genes of any two individuals belonging to the same species can eventually, over many generations, be mingled in the genome of a single, common descendant, and that this will happen without human intervention or disturbance of normal environments or habitats. In other words, there should be no geographical, anatomical or other absolute physical barriers that completely isolate any group of individuals from all other such groups of the same species.
Further, the offspring of any two individuals in a species (assuming they are of opposite sexes, or hermaphroditic), must be fertile and capable of interbreeding with other members of that species.
Special problems in defining species arise for animals which reproduce exclusively by parthenogenesis or simpler, asexual means, so that their ability to interbreed cannot be tested.
There are no absolute standards for the amount of genetic or morphological difference that must exist between two individuals to put them in separate species. Nevertheless, nearly all animal species are defined by their morphology. Interbreeding limits have been fully tested in only a tiny percentage of named species.

For a particular species name to be valid, it must be assigned in a refereed scientific journal.

The article in which the name is assigned must include a sufficient description of the organism to which it applies, and be published in one of a short list of accepted languages.

The meaning of the name must also be documented by one or more type specimens of the species that are given to a recognized museum for curation. The type specimens must be made available to any credentialed scientist who wishes to verify or enhance the original description, or compare the original type specimens with other specimens of the same or related species.

Binomial Nomenclature

The name of a species must always have two parts: a genus (plural: genera) name, and a specific epithet.

Example: Our specific epithet "sapiens" should never be written by itself, but always as Homo sapiens or H. sapiens.

The genus name must be unique, that is, never applied to any other type of organism.

The specific epithet does not have to be unique, and many species have the same or similar specific epithets.

Examples: Anolis carolinensis , Gastrophryne carolinensis, Terrapene carolina, Lissodendoryx carolinensis, Polymesoda caroliniana.
Notice in the examples that the ending of the epithet is changed to agree with the gender of the genus name.

The genus name is always capitalized and italicized (or underlined if hand-written).

Example: correct - Homo. INCORRECT - homo or Homo

The specific epithet is not capitalized, even when it is based on an otherwise capitalized place name.

Examples: epithets based on "Carolina" above.

The same is also true for epithets based on people's names
(However, plant names based on people or places are capitalized by botanists.)

Example: Hyla andersoni, named after a Mr. or Ms. Anderson

The full species name may, but does not have to, include subspecies or variety names following the specific epithet. When used for animals, these additional names must also be italicized (or underlined) and not capitalized.

The genus name may be abbreviated to its first letter after it has been printed in full earlier in the same document. The capital letter abbreviating the genus is still italicized.

Example: After using Homo sapiens in a document, one may refer to it throughout the rest of the document as H. sapiens.

However, if another species name with a genus name that starts with "h" is used in the same document, both genus names must be written in full wherever they occur.

Example If Hirudo medicinalis is mentioned together with Homo sapiens, neither Homo nor Hirudo should be abbreviated when they occur again in the same document.

The species binomial, when used properly and in a scientific publication, should have with it the last name(s) of the describing author(s).

The describing author(s) is (are) the scientist (or scientists) who assigns a name for the first time, and meets the other requirements for establishing the official name for that kind of animal.

The earliest version of rules for establishing species names was proposed by Karl Linne', a Swedish naturalist in the 18th century, who then proceeded to publish official descriptions of hundreds, perhaps even thousands, of species.

Linne' latinized his name to Carolus Linnaeus. Linnaeus, sometimes abbreviated L., is given as describing author with many of the most common species of plants and animals, including ours, Homo sapiens Linnaeus.

Notice that the describing author's name is capitalized but not italicized.

When the describing author's name is printed inside parentheses, it means that the original description of the species was assigned to a different genus than the one in which it is now classified.

Genera are continually being revised (taxonomically reorganized), and often broken up into more narrowly defined, new genera which must be given new names.
Example: Chironomus plumosus (L.). Linnaeus originally described this midge fly species as a member of Tipula , a genus which has subsequently been broken up into many new genera belonging to several different families of flies.

Maintained by Sam Mozley, s_mozley@ncsu.edu

Last modified on May 21, 2002