SPECIES ACCOUNTS
Phylogenetic list of described extant species
This website aims to list and count the known extant species
of the world grouped by how they are related to one another through evolution.
The Species Accounts website is a work in progress. Currently, about 11.0% of
described extant species are listed and the remainder have their place held as
described below in the Introduction. Contact us for more
information.
Compiled by: Stephen Gene Sullivan, Ph.D., M.D.
Contributors: Christine Metlen, B.F.A. (Amphibia, Anura, Squamata, Sauria, Serpentes)
Web Page Design: Elizabeth Ann Sullivan, B.A., M.A.
INTRODUCTION
Learn about the definitions and methods used for the Species
Account website.
SPECIES LISTS
Go directly to the list of species organized by group.
INTERNET LINKS
BOOKS AND ARTICLES
INTRODUCTION
This phylogenetic list of described extant species of the
world is called SPECIES ACCOUNTS because its purpose is to list and count the
number of species in each group known to be related to each other through
evolution.
The definition of species used is the most liberal and
relies on the species definition used by experts in the study of each taxonomic
group of organisms. In birds, species are usually clearly delineated by
breeding groups. In some corals, which exhibit extensive hybridization
and a reticular rather than dichotomous pattern of evolution, species
definition may be one of convenience. In such cases, species may have to
be defined by relying on recognizable groupings of physical, functional or
other traits, while realizing that species so defined may exist along a
seamless cline of organisms. Species definition is particularly difficult
with viruses and bacteria.
Only extant species are listed and counted; extinct species
are not included.
Only described species are listed. Experts in some
taxa estimate that the actual number of species existing today may in some
cases be up to 1000 times as many as those described.
This is a phylogenetic list, not a classification. The
names used of species, genus, family or higher grouping rely on the opinions of
experts in each taxonomic group. Species are grouped, listed and counted
solely on the basis of their closest relationships in evolution regardless of
their formal classification. The structure of the list therefore takes
the form of a family tree with each species shown in relation to its closest
relatives.
Among the over 1 million described extant species the detailed
relationships in evolution are seldom fully known. Several rules are
therefore used in preparing this list. One would like to insure that each
group of species listed was monophyletic at each level of the family
tree. For a group to be monophyletic, two conditions must be met:
first, all species in the group must have evolved from one single ancestor;
second, all descendants of that ancestor must be represented in the
group. If either criterion is not met, the group is considered a paraphyletic
group.
When considering the evolutionary relationships among all
known species, the second criterion is seldom met since the relationships of
many species are not precisely known. For this reason this list requires
that the first criteria be met, that is, that all species in a group descended
from a single ancestor, but allows the possibility that other species or groups
separately listed may actually belong in that group.
The most conservative opinion accepted by most experts in a
given taxon is used. In this way error is minimized. A newly
described species or group, if its relationships were not known, would be
placed by itself at the lowest branch on the tree where knowledge of its
evolutionary relationships was certain. With further knowledge this
branch would be moved further up the tree to its proper place.
This convention might be summarized as ‘errors toward the
base of the tree’. An example is the placement of the coelacanth,
Latimeria chalumnae. Latimeria is currently placed at the base of the
branch containing all the Jawed Vertebrates until such time as its position
further up the tree is understood.
The position of a species or group at the base of the tree
or at a ‘low branch’ does not necessarily imply early separation from other
groups in evolutionary time but may mean that its relationships are not more
clearly defined. An example of this is the various groups of viruses
which are placed at the base of the tree.
SPECIES ACCOUNTS is a work in progress. When a species
name is not yet available, its place on the list is held in one of two
ways. In a short list, the species may be given a temporary number.
An example is the genus Theligonum which contains 3 species. Theligonum
cynocrambe is named and space is held for the other 2 as ‘Theligonum
Currently, about 11.0% of
described extant species are listed and the remainder have their place held as
described above. Help with this project is welcomed.
Abbreviations used: sp
species (singular)
spp
species (plural)
Click here to go directly to: SPECIES LISTS
CONTACT US
Please send comments, corrections, or lists of names to be
included by regular mail to: Stephen Gene Sullivan, Ph.D., M.D., 533 East 13th
Street, New York, NY 10009, USA.
SELECTED REFERENCES
INTERNET LINKS:
GLOBAL
BIODIVERSITY INFORMATION FACILITY
NATIONAL
CENTER FOR BIOTECHNOLOGY INFORMATION TAXONOMY BROWSER
LIST OF
BACTERIAL NAMES WITH STANDING IN NOMENCLATURE
THE INTERNATIONAL PLANT NAMES
INDEX
INTERNATIONAL LEGUME
DATABASE & INFORMATION SERVICE
PHYLUM CTENOPHORA:
LIST OF ALL VALID SPECIES NAMES
A
PRELIMINARY CHECKLIST OF THE FLAT BARK BEETLES OF THE WORLD
DR.
BILLIE J. SWALLA (Deuterostomia and Tunicata)
CHRIS
CAMERON’S HOME PAGE (Hemichordata)
LIVINGUNDERWORLD
- AMPHIBIAN INFORMATION RESOURCE
BOOKS AND ARTICLES:
VIRUS TAXONOMY. CLASSIFICATION AND NOMENCLATURE OF
VIRUSES. SEVENTH REPORT OF THE INTERNATIONAL COMMITTEE ON TAXONOMY OF
VIRUSES. M. H. V. van Regenmortel, C. M. Fauquet, D. H. L. Bishop,
Eds. Academic Press, San Diego, 2000.
FIVE KINGDOMS. AN ILLUSTRATED GUIDE TO THE PHYLA OF
LIFE ON EARTH. Second Edition. L. Margulis and K. V.
Schwartz. W. H. Freeman, New York, 1988.
BERGEY’S MANUAL OF DETERMINATIVE BACTERIOLOGY. Ninth
Edition. J. G. Holt, N. R. Krieg, P. H. A. Sneath, J. T. Staley, S. T.
Williams. Williams and Wilkins, Baltimore, 1994.
HANDBOOK OF PROTOCTISTA. L. Margulis, J. O. Corliss,
M. Melkonian, D. J. Chapman, Eds. Jones and Bartlett, Boston, 1990.
THE EVOLUTION AND CLASSIFICATION OF FLOWERING PLANTS.
Second Edition. A. Cronquist. The New York Botanical Garden, Bronx,
1988.
THE PLANT-BOOK. A PORTABLE DICTIONARY OF THE HIGHER PLANTS. D.
J. Mabberley. Cambridge University Press, Avon, 1987.
AINSWORTH AND BISBY’S DICTIONARY OF THE FUNGI. Eighth
Edition. D. L. Hawksworth, P. M. Kirk, B. C. Sutton, D. N. Pegler.
CAB International, Oxon, 1995.
GRZIMEK’S ANIMAL LIFE ENCYCLOPEDIA. VOL. 1.
LOWER ANIMALS. H. C. B. Grzimek, Ed. Van Nostrand Reinhold, New
York, 1972.
GRZIMEK’S ANIMAL LIFE ENCYCLOPEDIA. VOL. 3.
MOLLUSKS AND ECHINODERMS. H. C. B. Grzimek, Ed. Van Nostrand
Reinhold, New York, 1972.
IMM’S GENERAL TEXTBOOK OF ENTOMOLOGY. Tenth
Edition. 2 Vols. O. W. Richards and R. G. Davies. John Wiley,
London, 1977.
A WORLD CATALOGUE OF FAMILIES AND GENERA OF CURCULIONOIDEA
(INSECTA: COLEOPTERA) (EXCEPTING SCOLYTIDAE AND PLATYPODIDAE). M. A.
Alonso-Zarazaga and C. H. C. Lyal. Entomopraxis, Barcelona, 1999.
THE PHYLOGENY AND HIGHER CLASSIFICATION OF THE STAPHYLINIDAE
AND THEIR ALLIED GROUPS (COLEOPTERA, STAPHYLINOIDEA). Shun-Ichiro
Naomi. ESAKIA (23): 1-27, 1985.
MOLECULAR PHYLOGENY OF THE PROTOCHORDATES: CHORDATE
EVOLUTION. L. Zeng and B. J. Swalla. CAN. J. ZOOL. (83): 24-33,
2005.
FISHES OF THE WORLD. Third Edition. J. S. Nelson.
John Wiley, New York, 1994.
WALKER’S MAMMALS OF THE WORLD. Sixth Edition. 2 Vols. R. M. Nowak. Johns Hopkins University Press, Baltimore, 1999.