Official, scientific names are assigned to
A taxon (plural, taxa)
is a group of organisms that are, to some degree or level, anatomically
and (presumably) genetically similar.
Ideally, by modern standards, a taxon should be monophyletic, that is,
include the most recent common ancestor of all its members, as well as
descendants of that common ancestor. This is not true for many,
taxa, including Turbellaria and Crustacea.
The standard of monophyly has caused much disruption in the use of
by zoologists, both in teaching and research.
Taxa are arranged in a hierarchy of successively smaller and more
Examples of names of levels of taxa in this hierarchy are phylum,
family, and species.
Scientific names for higher taxonomic levels sometimes vary according
schools of thought.
When a scientist argues for a new name or newly recognized grouping,
of her or his colleagues will accept it and others will not.
But after a few decades of debate, biologists usually come to agreement
on the names that are used for higher taxa.
Scientific names for taxonomic levels above genus are capitalized but
and not underlined when handwritten
for example, Gastrotricha, Coleoptera, Gyraulidae
Scientific names are said to be "anglicized" when the endings are
to English format.
Anglicized names should not be capitalized.
For example, the phylum name Gastrotricha becomes "gastrotrich" when
Gyraulidae becomes "gyraulid," and Coleoptera becomes "coleopteran."
Anglicized names are treated the same as common names (see below).
The term species means a taxon of organisms whose members are capable
at least occasionally in nature
without human intervention or disturbance.
The scientific name for a species of organism is the same in all
- The name of a species (plural: species)
must always include both:
a genus (plural: genera)
which is unique (never used for any other kind of organism outside this
and a specific epithet.
The specific epithet for the common stream crayfish, "bartoni," should
never be used alone, but always as Cambarus bartoni.
The specific epithet does not have to be unique.
Many species have the epithet "carolinensis," for example, Acroneuria
The epithet is treated like an adjective that modifies the genus name,
which itself is treated as a noun.
Notice that the epithet "carolinensis" above is not capitalized, even
it is based on a capitalized place name.
The same is true for specific epithets based on people's names (at
in zoology), such as Hydroporus blanchardi Sherman.
The name "(Banks)" after the species name above is the describing
His name is in parentheses because he described and named the species
a different genus name, perhaps "Perla carolinensis."
Later, someone changed the species into a new genus, but the epithet
describing author's name were retained.
The author's name is supposed to be attached to the species name in
scientific publication the first time it is used, in the text or a
but this rule is often ignored in non-taxonomic articles.
This does not apply to the genus author's name, which needs only to be
given in papers dealing mainly with taxonomy or systematics.
The genus name is always capitalized AND italicized (or underlined, if
Helobdella or Helobdella,
helobdella or Helobdella
The full species name may, but does not have to, include subspecies or
variety epithets following the specific epithet.
For example, Crangonyx richmondensis richmondensis Ellis
These additional epithets are also italicized but not capitalized.
The name after the subspecies name ("Ellis") is the describing author
Like the species author's name (which is not required if the subspecies
author is different), it should be capitalized but not italicized or
The genus name may be abbreviated to its first letter after it has been
given in full the first time it occurs in a document.
After first using the full species name Skistodiaptomus reighardi (Marsh),
authors may refer to it as S. reighardi.
However, if another species is named whose genus name starts with
the whole genus names should be used if there is any chance of
For example if Spongilla lacustris (L.) is listed in the same
Skistodiaptomus reighardi, the author would have to
both Spongilla and
in full every time they
Describing a New Species, or Defining an
The rules and requirements for official species descriptions include:
placing reference, "type" specimens in recognized museums or other
publishing a full morphological description of adult life stages in a
scientific journal, in one of a few, widely used or classical languages.
review and approval of the article before it is published by a panel of
The scientist (or scientists) who first does this, and thereby selects
the official name for the species, is called the describing author.
That scientist's name follows the species name in taxonomic
for example, Chironomus plumosus (Linnaeus)
- Linnaeus's name is put in parentheses because he originally
small midge under a different genus name, "Tipula plumosa Linnaeus"
Notice that, when the species was moved to a new genus, the ending of
specific epithet had to change to match the gender of the new genus
the epithet is treated like an adjective in Latin and must agreed with
the modified noun in gender.
- Some years after Linnaeus originally described Tipula
Meigen split the very large genus Tipula into several new
and genera, including Chironomus.
- Linnaeus still gets credit as the describer of the species,
but now his
name is shown in parentheses.
- If the genus name has not changed since the species was
author's name is not put in parentheses.
For example, Sperchonopsis ecphyma Prasad and
The earliest version of these rules was proposed by Karl Linne'.
He was a Swedish naturalist in the late 18th century.
He published the first official descriptions of thousands of species,
in Latin or Greek.
He "latinized" his name to Carolus Linnaeus.
You will see the name Linnaeus, often abbreviated "L." because he was
well known, after many of the world's most common species of plants and
animals, including ours,
Homo sapiens L.
Common names are not officially defined.
The common name of the same animal may differ between languages,
or even within a single community.
Field biologists have standardized at least the English common names of
some groups (e.g., fish, birds) for use in specialists' publications,
other scientists outside those societies are not obligated to follow
Common names are generally not capitalized (except as required
For example, mayfly, snail, flatworm, hellgrammite, crayfish, etc.
However, ornithologists have determined that common names of birds are
standardized and should be capitalized in ornithological publicatons.
In rare cases, the scientific name and common name for a genus are the
An example is "hydra."
When the name is intended to apply to a particular genus of hydras, it
should be capitalized and italicized.
- When hydra is meant to refer to an unidentified animal with a
body form (possiblyHydra,
etc.), it is written lower case and not italicized.
Maintained by Sam Mozley, email@example.com
Last modified on April 21, 2004