Compiled by Stephen Gene Sullivan, Ph.D., M.D.
Contributors: Amphibia, Anura, Squamata, Sauria, Serpentes Christine Evelyn Sullivan, B.F.A.
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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 Coriaria which contains 5 species. Coriaria myrtifolia is named and space is held for the other 4 as ‘Coriaria 2’, ‘Coriaria 3’, etc. In longer lists, space is held by using the word ‘Other’ before the group name. The family Viscaceae contains 449 species. Phorandendron serotinum and four other species are named and space is held for the other 444 as ‘444 Other Viscaceae’.
Currently, about 10.7% of
described extant species are listed and the remainder have their place held as
described above. Help with this project
is welcomed. 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.
Abbreviations used:
sp species (singular)
spp species (plural)
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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
CLASSIFICATION AND SYSTEMATICS OF THE ICHNEUMONIDAE
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.