Rules for assigning scientific names have become well codified in order to
keep the names internationally unambiguous and understandable. The full
set of rules is rather involved, but the most important parts are fairly
- Binomens - A genus name is one word. A species name is
binomial -- the genus plus a second word. Subspecies have a trinomial
name (a "trinomen"). A subgenus is occasionally given in parentheses
after the genus, thus:
Bison (Bison) bison bison (Linne, 1758) Skinner & Kaisen,
1947 (American bison)
- Authorship -
The author's name and date of publication are typically given after the
scientific name. If a name is later changed (e.g., moved to a new genus),
The original author is given in parentheses. The names are often
abbreviated; in particular, "L." is Linnaeus.
Anonymous publication is invalid as of 1950, but was accepted before
Buettikoferella Stresemann, 1928
(buff-banded grassbird) This name was originally published in an obituary.
Stresemann mentioned, in an obituary for Buettikofer, that a bird genus
was named after him, but Stresemann realized that Buettikoferia was
preoccupied, so he proposed this as a replacement. [Orn. Monatsb.
- Description - After 1930, new names must come with a description
(or reference to one) telling what the name means.
Megalochelys atlas (Rhodin et al. 2015)
(giant Miocene-Pleistocene turtle) The fossil was first
named Megalochelys sivalensis by Falconer & Cautley (1837),
but that publication was a brief announcement with no description.
They gave a complete description in 1844, but changed the name
to Colossochelys atlas (because they felt that
"Megalochelys" was not sufficiently expressive of the fossil's
large size). A nomen nudum, or "naked name", i.e. a name
without description, invalidates the species name but not, it turns
out, names of genus or higher rank, so Megalochelys stayed,
but sivalensis was replaced by atlas. (And Rhodin et
al. get credit for first treating it under that combination
[Turtles and Tortoises of the World during the Rise and Global
Spread of Humanity].)
- Type specimen - Descriptions should refer to an actual
specimen, available for examination in a museum or other collection.
There are complicated rules for determining the type if the original is
lost or if there was no type specimen with the original description. The
taxonomy of types is rather complicated in itself; see this
In a 1959 article on Linnaeus, William Stearn wrote, "Linnaeus himself,
must stand as the type of his Homo sapiens." Though it was an
off-hand comment, it suffices as nomenclatural act, and so Linnaeus,
buried beneath Uppsala Cathedral, is the lectotype (a later-selected
type specimen) for Homo sapiens. A 1994 publication reported
that Robert Bakker proposed to designate Edward Cope as the type, but
Bakker never actually published this. Besides, Stearn's designation has
Nessiteras rhombopteryx (Loch Ness monster) This
proposed name is not a valid scientific name because there is no type
specimen to go with it.
- Priority - The oldest valid published name is the one that
gets used. Today one need not look back further than the works of
Linnaeus, but Linnaeus and his students searched older works for the
oldest published names, going back even to Thucydides and Pliny the
Elder. Early publication is not invalidated even if there is some error
in the original name:
Cryptoclidus (plesiosaur from Oxford Clay)
The spelling was intended to be Cryptocleidus (from the Greek
for 'hidden clavicle'), but probably from a printing error, it
appeared, and now remains, without the 'e'.
Eschscholzia Chamisso, 1820 (California
poppy) Named for zoologist Johann Eschscholtz, but the 't' was omitted
from the publication.
Haliaeetus Savigny, 1809 (bald eagle) This name is a
misspelling; the original description had an extra 'e', which must now
Huernia (African Asclepiadaceae) Named after
Justus Heurnius, the first European to collect plants in South Africa,
but the "eu" was transposed in publication.
Wisteria Nuttall (woody vine) Named for
Caspar Wistar, author of America's first anatomy textbook and successor
of Thomas Jefferson as head of the American Philosophical Society. But
Nuttall misspelled it with an "e", and the name is stuck.
Amblystoma Tschudi 1838 (mole salamanders)
Both names appeared in the original description. Amblystoma
("blunt mouth") was probably intended, but Ambystoma (and the
family Ambystomatidae) is the accepted name now. Amblystoma is
on the Official Index of Rejected and Invalid names, but it still gets
quite a bit of use.
- There are means of overruling priority, if the newer name has come
into common use before the priority of the original name is recognized.
Scrotum humanum Brookes, 1763 (Megalosaurus) Among the
oldest dinosaur bones discovered. So named because the condyles had a
testicular shape. Fortunately, the genus will continue to be known as
Megalosaurus because that name came into common use before it was
discovered that Scrotum was an earlier synonym. [Halstead &
Sargent, 1993, Modern Geol. 18:221-4]
- Sometimes the same name gets reused by people not aware of the
Argus Bohadsch, 1761 (gastropod)
Argus Scopoli, 1763 (lycaenid)
Argus Scopoli, 1777 (satyrid)
Argus Poli, 1791 (mollusk)
Argus Temminck, 1807 (bird)
Argus Lamarck, 1817 (hesperiid)
Argus Boisduval, 1832 (lycaenid)
Argus Walckenaer, 1836 (arachnid)
Argus Gray, 1847 (mollusk)
Argus Gerhard, 1850 (lycaenid)
Only the original name is valid. Since that name has priority, all the
rest are junior homonyms and needed to be renamed.
- However, the same name can be used for a plant and an animal. There
are many instances:
Adonis L., 1753 (bird's-eye ranuncula) or
Adonis Gronow, 1854 (fish)
Ammophila (grass, or sphecid wasp)
Andromeda L., 1753 (wild rosemary) or
Andromeda Gistel, 1834 (bupestrid
Arenaria L. 1753 (Caryophyllaceae plant) or
Arenaria Brisson 1760 (bird)
Aotus (pea, or monkey)
Arctophila (grass, or syrphid fly)
Aristotelia (tree, or moth)
Bartramia (moss, or sandpiper)
Cannabis L. (hemp) or
Cannabis Blyth, 1850 (bird)
Cecropia (tree, or moth)
Cereus (cactus, or sea anemone)
Chloris (grass, or green finch)
Colocasia (taro, or tussock moth)
Culcita (tree fern, or echinoderm)
Cyanea (Hawaiian bellflower, or jellyfish)
Darwinia Rudge, 1815 (shrub), or
Darwinia Pereyaslawzewa, 1892 (flatworm)
Darwiniella Speg. 1888 (fungus), or
Darwiniella Anderson, 1992 (barnacle)
Darwiniella (orchid, or barnacle)
Dracunculus (herb, or roundworm)
Dryas (shrub, or butterfly) The shrub gave
its name to the Older and Younger Dryas geological periods.
Dugesia (composite, or flatworm)
Eisenia (brown alga, or earthworm)
Erica L. (heath) or
Erica Peckham and Peckham 1892 (jumping
Ficus (fig, or gastropod)
Hamadryas (buttercup, or butterfly)
Hystrix (grass, or porcupine)
Iris (flower, or mantis)
Knightia (Proteaceae plant, or fossil fish)
Lactarius (fungus or fish)
Leptonia (toadstool (now usu. a subgenus of
Entoloma), or rove beetle)
Liparis Rich., 1818 (orchid) or
Liparis Scopoli, 1777 (fish)
Megaceros (hornwort, or Pleistocene
Morus (mulberry, or gannet)
Oenanthe (water celery, or bird)
Pieris (Japanese andromeda, or butterfly)
Ponera Lindl. (orchid) or
Ponera Latreille, 1804 (ant)
Prosopis (mesquite, or solitary bee)
Prunella Linnaeus 1753 (Lamiaceae plant) or
Prunella Vieillot 1816 (bird). In fact, each genus
Rhamphorhynchus (orchid, or
Ricinus (castor bean, or bird louse)
Sirindhornia (orchid, or moth)
Sphaerostoma (fossil gymnosperm, or
Stenella Syd. (1930) (fungus) or
Stenella Gray, 1866 (dolphin)
Trichia von Haller 1768 (slime mold) or
Trichia Hartmann 1840 (snail)
Verticordia DC. (myrtle) or
Verticordia Sowerby, 1844) (clam)
Zenkerella (African legume, or African
Zeus Minter & Diam. (1987) (fungus) or
Zeus L. (dory)
- Words and Letters - The names must be pronouncible words
(preferably Latinized), using Latin letters, with no diacritics or
punctuation (except hyphens can be used in some circumstances).
Some names stretch the pronouncibility.
Ekgmowechashala (early Miocene North American primate)
The name means "small fox-man" in Lakota
Lainodon orueetxebarriai Gheerbrant & Astibia,
1994 (Upper Cretaceous mammal) The 'tx' is pronounced like
Nqwebasaurus thwazi de Klerk et al., 2000 (Late
Jurassic/Early Cretaceous South African coelurosaur) It is pronounced:
N-(click with tongue)-KWE-bah-SAWR-us. If you are a real stickler for
pronunciation, the "nq" is a nasal postalveolar click. Nqweba is the
native Bantu name of the place where the dino was found.
Schtschurowskia Regel & Schmalhausen, 1882
Tahuantinsuyoa macantzatza Kullander, 1986
(Peruvian cichlid) The genus is a Quechuan name of the Incan empire;
has a pronunciation.
There are no official rules about how names should be
pronounced. Still, many names have right and wrong pronunciations
according to conventional usage.
Buddleja L. (shrub) Named after botanist
and rector Adam Buddle in an era when 'j' sometimes signified a long
'i' between two vowels. It is pronounced BUD-ul-EYE-uh.
There are plenty of other rules; see the
ICZN and specifically the
Code of Zoological Nomenclature for the complete set.
- Exceptions - When an otherwise valid name would "disturb
stability or universality or cause confusion," the International
Commission on Zoological Nomenclature may choose another name instead.
The rules above are for zoological nomenclature. The
rules for botanical
nomenclature are similar. Some exceptions are:
- For valid publication, after Jan. 1, 1935 (1958 for algae, 1996
for fossils), the plant name must be accompanied by a Latin
description or diagnosis, or by a reference to one.
- Publication of species or lower ranks must, after 1912 (1958 for
algae), be accompanied by an illustration showing essential
characters, or by a reference to one. After 2001, one such
illustration must represent the type specimen.
- The authors are given in taxonomic
monographs, and if a name is changed, both the original author (in
parentheses) and the revising author are named. For example:
Taphrina cerasi (Fuck.) Sad. The fungus
Taphrina cerasi was originally described by Karl Wilhelm Gottlieb
Leopold Fuckel and later redescribed by Richard Emil Benjamin
Sadebeck, so this listing now appears in some catalogs. The prefered
citation, though, is Taphrina cerasi (Fuckel) Sadeb.
- Zoology allows tautonyms (genus and species repeating the same
word, e.g. Bufo bufo), and botany does not. Some names
come close, though.
Ziziphus zizyphus (L.) H.Karst. (jujube)
- Zoologists do not like hyphens in names (although a very few have
Polygonia c-album (Linnaeus, 1758), the
Xestia c-nigrum (Linnaeus, 1758), the
Setaceous Hebrew character (a moth), and
Phelsuma v-nigra (Boettger, 1913), a gecko,
are the only I know of).
Botany does not encourage hyphens, but allows them more freely:
Johnson-sea-linkia profunda N.J. Eiseman &
S.A. Earle, 1983 (seaweed)
- Rules for botany (at least since 1912) forbid generic names which
refer to morphological characters.
- The International Code of Nomenclature for algae, fungi, and
plants goes into great length concerning the messy subject of
hybrids. Orchids present enough additional difficulties in this
area that they have their own Handbook on Orchid Nomenclature and
- Botany allows names for ranks below subspecies: variety (var.),
subvariety (subvar.), form (f.), and subform (subf.). These need
not be nested within a subspecies or each other.
Traditionally, fungi have been grouped with plants (even though, as
later discovered, they are more closely related to animals). In 2011,
this grouping was formalized, with the botanical code (ICBN) renamed
the International Code of Nomenclature for algae, fungi, and
Because fungi often have very different sexual and asexual forms, the
same species of fungus could have two different scientific names, one
for the sexual form and one for the asexual. This rule, however, has
changed (with much gnashing of teeth) as of 2011, because DNA analysis
makes it easier to recognize two forms as the same species.
There is also a separate International Code of Nomenclature of
Prokaryotes governed by the International Committee on Systematics of
Prokaryotes (ICSP). It has published the Approved Lists of Bacterial
Names, listing all names valid as of 1 January 1980; it serves as a
starting point for adding new names. "(Approved Lists 1980)" may be used
in place of an author citation for names on the lists.
Other rules particular to prokaryotes are:
- Names must be published in International Journal of Systematic
Bacteriology or International Journal of Systematic and
Evolutionary Microbiology to be valid.
- Subgenus and subspecies names, when present, are labelled "subgen."
- Prokaryote names must avoid existing names of plants and
animals. For some reason there is one exception:
Bacillus Lepetelier & Audinet-Serville, 1828 (stick
insect) or Bacillus Cohn, 1872 (bacterium)
- The Code recommends that if a species is named after a person, the
person should in some way be connected with it.
- A name should be rejected "whose application is likely to lead to
accidents endangering health or life or both or of serious economic
See also Trüper 1999 in the references.
Last modified: .
All rights reserved.
Mark Isaak's Home Page