1. Introduction to Scientific Nomenclature
Hendrik Segers1 & Yves Samyn2
1Belgian Platform Biodiversity
2Belgian Focal Point for the GTI
Royal Belgian Institute of Natural Sciences
Vautierstraat 29
B-1000 BRUSSELS (Belgium)

2. Background observations and definitions
Living organisms are grouped:
Any group of organism = taxon (taxa)
Taxa are arranged in a series of levels (taxonomic hierarchy)
Levels of taxonomic hierarchy have different names (taxonomic ranks; e.g. genus, family, order, class, phylum)
Taxa at the same level belong to the same taxonomic category
The Codes of Nomenclature are the tools used to name taxa, and to determine which of alternatives is the correct one.

3. Why nomenclature?
Fundamental aim of nomenclature: avoid a Tower of Babel
“The objects of the Code are to promote stability and universability in the scientific names of animals and to ensure that the name of each taxon is unique and distinct.
All its provisions and recommendations are subservient to those ends and none restricts the freedom of taxonomic thought or actions”
(ICZN 1999:2)

4. History of scientific nomenclature
Taxa have always been named and classified (e.g. Greek and Roman naturalists; medieval herbalists; folk taxonomists: vernacular names)
Pre-Linnaean naturalists:
names in Latin
nomina specifica; binominal, trinominal or even polynominal names (e.g. Iris perpusilla saxatilis Norbonensis a caulis ferme)
names inconsistent and often paragraphs long (diagnosis, description, identification purposes)
Linnaeus’ 18th century taxonomic system [cf. Species plantarum (1753) and Systema naturae (1758)]
nomina trivialia; always binominal in structure
diagnostic style
Need for universal codes became prominent

5. Nomenclature codes
Greuter, W., et al. (eds), International Code of Botanical Nomenclature (St Louis Code). Regnum Vegetabile 138. Koeltz Scientific Books, Königstein. ISBN
Trehane, P., et al. (eds) International Code of Nomenclature for Cultivated Plants. Adapted by the International Committee for the Nomenclature of Cultivated Plants of the I.U.B.S. Regn. Veget. 133.
Sneath, P.H.A., et al. (eds), International Code of Nomenclature of Bacteria. Washington (+ : Skerman, V.D.B. et al., Approved Lists of Bacterial Names).
International Commission on Zoological Nomenclature, International Code of Zoological Nomenclature, 4th edition. Adopted by the I.U.B.S. The International Trust for Zoological Nomenclature, London.

6. History of zoological nomenclature
1758 Formal starting point = 10th Edition of Linnaeus’s Systema Naturae (also Clerck’s Aranei Svecici)
1842 Strickland Code (botany and zoology)
1889 First ICZ meeting (Paris); tentative adoption of a set of rules
1901 Fifth ICZ meeting (Berlin); “Rules of Zoological Nomenclature”; published as Règles Internationales de la Nomenclature Zoologique (French, English & German)
1961 First edition of the Code of Zoological Nomenclature
1964 Second edition
1985 Third edition (glossary added; no more discrimination between French and English)
1988 Launch of fourth edition project
1995 Draft of fourth edition released by Secretariat
Distribution of hard copies
Discussion forum on internet
New concepts and provisions published in Bull. Zool. Nomenclature
1999 Fourth edition (current edition)
Takes effect from 1 January 2000
Cladists already perceive it as too prescriptive (taxa and their names forced in arbitrary ranks of Linnean hierarchy) and too permissive (applies also to non-monophyletic groups)

7. Why do names change? Increased scientific understanding
(e.g., discoveries; changes in species concept (s.l.) and phylogenetic understanding)
Correct application of nomenclatural codes
(e.g., correction of errors; homonyms;…)

8. Why do names change?
Increased scientific understanding
(e.g., discoveries; changes in species concept (s.l.) and phylogenetic understanding)
Correct application of nomenclatural codes
(e.g., correction of errors; homonyms;…)
All changes are governed by legalistic, scientifically neutral conventions: the codes of nomenclature
E.g.: the ICZN (1999; consists of:
Preamble
90 Articles, grouped in 18 chapters
One or more mandatory provisions
Non-mandatory recommendations
Examples
Glossary

9. Nomenclature only follows taxonomy
Ruling principles
Nomenclature = naming tool
Nomenclature only follows taxonomy

10. The taxonomic identity of a name is determined by that of its type
Ruling principles
Nomenclature = naming tool
Typification
The taxonomic identity of a name is determined by that of its type

11. Principle of Typification
Art Each nominal taxon in the family, genus or species groups has actually or potentially a name-bearing type. The fixation of the name bearing type of a nominal taxon provides the objective standard of reference for the application of the name it bears.
The valid name from a taxon is determined only from the name-bearing type(s)
Objectivity through typification is continuous through the hierarchy of names, from species to family group
Name-bearing types (generally) are stable and provide objective continuity in the application of names
(ICZN)
=> Identity of a name relies only on its type, not on its description or diagnosis

12. 1 taxon should only have 1 name
Ruling principles
Nomenclature = naming tool
Typification
Principle of Synonymy
1 taxon should only have 1 name

13. Ruling principles Principle of Homonymy
Nomenclature = naming tool
Typification
Principle of Synonymy
Principle of Homonymy
1 name can apply to only 1 taxon
(but see independance of codes)

14. “the oldest fool is always right”
Ruling principles
Nomenclature = naming tool
Typification
Principle of Synonymy
Principle of Homonymy
Principle of Priority
“the oldest fool is always right”

15. Principle of bionominal nomenclature
Names of taxa above species: uninominal: e.g., Hominidae, Homo
Names of species: binominal: e.g., Homo sapiens

16. Monostyla closterocerca Schmarda, 1853
What’s in a name?
Species name: binomen
Monostyla closterocerca Schmarda, 1853

17. Lecane (Monostyla) closterocerca (Schmarda, 1853) Edmondson, 1935
With subgenus name: binomen
Lecane (Monostyla) closterocerca (Schmarda, 1853) Edmondson, 1935

18. Lecane (M.) closterocerca (Shmarda, 1853)
Short:
Lecane (M.) closterocerca (Shmarda, 1853)
Or (zoology!):
L. closterocerca

19. With subspecies name: trinomen
Lecane (Monostyla) closterocerca amazonica Koste, 1972 non Murray, 1913

20. L. closterocerca amazonica Koste, 1972
Short:
L. closterocerca amazonica Koste, 1972
Or (zoology!):
L. closterocerca amazonica

21. In botanic nomenclature:
Phragmites autralis (Cavanilles) Trinius ex Streudel:
Streudel published Trinius’ suggestion

22. Scientific Names are Latin
Rules of Latin grammar apply
Agreement in gender

23. Scientific Names are Latin
Rules of Latin grammar apply
Agreement in gender
Mastigocerca capucina Wierzejski & Zacharias, 1893
Rattulus capucinus : Jennings, 1903
Trichocerca capucina (Wierzejski & Zacharias, 1893) Harring, 1913

24. Formation of Scientific Names
Formation of species names:
After features: adjectives
e.g.:
Lepadella minuta
Scaridium grande
S. longicaudum
Brachionus bidentatus
Keratella taurocephala

25. Formation of Scientific Names
Formation of species names:
After features: adjectives
After other species: noun in apposition, adjective
e.g., Trichocerca tigris, T. rattus, T. cavia, T. mus, T. musculus, T. porcellus, T. orca.
also: Seison nebaliae.

26. Formation of Scientific Names
Formation of species names:
After features: adjectives
After other species: noun in apposition, adjective
After people: noun in genitive case
one man: Lecane shieli or L. ludwigii
one woman: Lecane robertsonae
several man/woman: L. gallagherorum
several woman: stem + arum

27. Formation of Scientific Names
Formation of species names:
After features: adjectives
After other species: noun in apposition, adjective
After people: noun in genitive case
After places: adjectival toponym
e.g., Lecane papuana
Brachionus budapestinensis

28. Formation of Scientific Names
Formation of species names:
no diacritic or other marks, ligature, apostrophes, etc…:
Trichocerca dixon-nutalli becomes T. dixonnutalli;
Dicranophorus lütkeni becomes D. luetkeni;
Filinia novaezaelandiae;
(ñ becomes n, ø becomes o, …)
But
- Zygiella x-notata

29. Principle of Typification
Type: sole bearer on identity of a name
Description, diagnosis,… are required,
but irrelevant
(for nomenclatural purposes)

30. Principle of Typification
Types of name-bearing types (in the species group)
Original designation
(Fixed in the original publication)
Subsequent designation
(Not fixed in the original publication)
Holotype: the single specimen upon which a new species-group taxon is based in the original publication (see also isotype)
Paratypes: remaining specimens of the original type series (see also allotype)
Syntypes: specimens of a type series that collectively constitute the name-bearing type
Hapantotype: (special case)
Lectotype: a syntype designated as the single-name bearing type specimen
Paralectotypes: each specimen of the former syntype series remaining after lectotype designation (see also isolectotype)
Neotype: the single specimen designated as the name-bearing type when no name-bearing type specimen is believed to exist (anymore)

31. Principle of Typification
Terms not regulated by the Codes
Allotype: a designated specimen of opposite sex of the holotype
Cotype: a term formerly used for either syntype or paratype
Genotype: a term formerly used to designate the type species of a genus (generotype)
Topotype: a specimen originating from the type locality or localities of the species or subspecies to which it is thought to belong, whether or not the specimen is part of the type series (see also topotypical specimen)
Some peculiar cases: Cleptotype, Iconotype, …
Type of a family name = genus
Type of a genus = species

32. Q: Can the real Pinus please stand up?
How does it work?
Genus Pinus Linnaeus, 1753 (pine trees)
Taxonomy: five distinct genera 
  Genus 1 : P. cedrus
Genus 2 : P. larix
Genus 3 : P. picea, P. balsamea
Genus 4 : P. abies
Genus 5 : P. sylvestris, P. pinea, P. cembra, P. strobus, P. taeda.
Q: Can the real Pinus please stand up?

33. How does it work? Taxonomy: five distinct genera Genus 1 : P. cedrus
Genus 2 : P. larix
Genus 3 : P. picea, P. balsamea
Genus 4 : P. abies
Genus 5 : P. sylvestris, P. pinea, P. cembra, P. strobus, P. taeda.
Type of Pinus : P. sylvestris. Hence, = (5)
Others: new names (Cedrus, Larix, Abies and Picea, respectively).

34. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Nomenclatural (= objective, homotypic) synonyms
(e.g., replacement names: nomina nova, …)

35. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Nomenclatural (= objective, homotypic) synonyms
Taxonomic (= subjective, heterotypic) synonyms
(most common)

36. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Nomenclatural (= objective, homotypic) synonyms
Taxonomic (= subjective, heterotypic) synonyms
Lecane ludwigii (Eckstein, 1883) or
Lecane stokesi (Pell, 1890) or
Lecane ohioensis (Herrick, 1885) ?

37. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Homonyms: 1 name = 2 or more taxa
e.g.,
Argus Bohadsch, 1761(gastropod);
Argus Scopoli, 1763 (butterfly);
Argus Scopoli, 1777 (butterfly);
Argus Poli, 1791 (mollusk);
Argus Temminck, 1807 (bird);
Argus Lamarck, 1817 (hesperid);
Argus Boisduval, 1832 (lycaenid);
Argus Walckenaer, 1836 (arachnid);
Argus Gray, 1847(mollusk);
Argus Gerhard, 1850 (lycaenid))

38. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Homonyms: 1 name = 2 or more taxa
Lecane ornata (Harring & Myers, 1926)
Lecane ornata (Daday, 1897)
(syn. of L. ludwigii (Eckstein, 1883))

39. Synonyms and Homonyms Synonyms: 2 or more names = 1 taxon
Homonyms: 1 name = 2 or more taxa
Lecane ornata (Harring & Myers, 1926)
Lecane ornata (Daday, 1897)
(syn. of L. ludwigii (Eckstein, 1883))
Problem: name for L. ornata (Harring & Myers, 1926) non (Daday, 1897)?

40. Principle of Priority:
Synonyms and Homonyms
Synonyms: 2 or more names = 1 taxon
Homonyms: 1 name = 2 or more taxa
Who’s right?
Principle of Priority:
“the oldest fool is always right”

41. Lecane ludwigii (Eckstein, 1883)
Synonyms and Homonyms
Synonyms: 2 or more names = 1 taxon
Lecane ludwigii (Eckstein, 1883)
Lecane stokesi (Pell, 1890)
Lecane ohioensis (Herrick, 1885)
« Oldest fool »:
Lecane ludwigii (Eckstein, 1883)

42. No “Oldest fool” available!
Synonyms and Homonyms
Homonyms: 1 name = 2 or more taxa
Lecane ornata (Harring & Myers, 1926)
Lecane ornata (Daday, 1897)
(syn. van L. ludwigii (Eckstein, 1883)
Problem: name for L. ornata (Harring & Myers, 1926) non (Daday, 1897)?
No “Oldest fool” available!
Nomen novum required:
Solution: L. myersi Segers, 1993

43. Principle of Priority: But This Can Cause Problems
Synonyms and Homonyms
Synonyms: 2 or more names = 1 taxon
Homonyms: 1 name = 2 or more taxa
Who’s right?
Principle of Priority:
“the oldest fool is always right”
But This Can Cause Problems
The commission can intervene!
(nomina rejicienda, conservanda)

44. Formal requirements in ICZN (1)
Name or nomenclatural act must be Published;

45. Formal requirements in ICZN (1)
Name or nomenclatural act must be Published;
Scientific names must be spelled using the 26 letters of the Latin Alfabet;

46. Formal requirements in ICZN (1)
Name or nomenclatural act must be Published;
Scientific names must be spelled using the 26 letters of the Latin Alfabet;
Consistent application of binominal nomenclature in the work in which the new name or nomenclatural act is published;

47. Formal requirements in ICZN (1)
Name or nomenclatural act must be Published;
Scientific names must be spelled using the 26 letters of the Latin Alfabet;
Consistent application of binominal nomenclature in the work in which the new name or nomenclatural act is published;
Derivation: a name may be derived from any language, or even an arbitrary combination of letters if this is formed to be used as a word (not cbafdg);
=> lots of freedom allowed!

48. Some examples…. One-letter difference:
Genus Eucosma (Moths, Northern Mexico: Kearfoot, 1907)
E. fandana
E. gandana
E. handana
E. kandana
E. mandana
E. nandana
E. pandana
E. randana
E. sandana
E. tandana
E. vandana
E. wandana
E. xandana
E. yandana
E. zandana

49. More examples…. Fun with Latin:
Stupidogobius Aurich, 1938 (stupid fish)
Localities:
Panama canalia Marsh, 1993(braconid)
Australia Girault, 1928 (parasitic wasp);
Babylonia Schlulter, 1838 (mollusk);
Mythology:
Zeus Linnaeus, 1758 (fish), Kali Lloyd, 1909 (fish)
Satan Hubbs & Bailey, 1947 (fish),…

50. Even more examples…. Persons (“honorifics”):
Cartwrightia cartwrighti Cartwright, 1967 (scarab)
Hoia hoi (parasitic copepod), after Ju-Shey Ho
Leonardo davincii Bleszynski, 1965 (pyralid butterfly)
But also:
Dyaria Neumoegen, 1893 (liparid butterfly) after Mr. Dyar.
Not another one…
Cyclocephala nodanotherwon Ratcliffe (scarabid)
Trombicula doremi Brennan & Beck, 1955; Trombicula fasola Brennan & Beck, 1955 (mites)

51. Formal requirements in ICZN (2)
Names to be used as valid when proposed
(no conditional proposal)

52. Formal requirements in ICZN (2)
Names to be used as valid when proposed
Publication of a name as a synonym does not thereby make the name available;

53. Formal requirements in ICZN (2)
Names to be used as valid when proposed
Publication of a name as a synonym does not thereby make the name available;
New requirements for species-group names published after 1999:
Explicit indication of name as intentionally new
(n.sp., gen. nov., nom. nov.,…)
Fixation of name-bearing types explicit
designation & deposition

54. The different codes: a comparison

55. The different codes: a comparison
The codes have different starting dates and works
Botanical : Species Plantarum : Linnaeus, 1753.
Zoological : Systema Naturae : Linnaeus, 1758; Araneae swecici Clerck, 1757,…
Bacteriologial : January 1, 1980 (older names only when included in list of approved names)

56. The different codes: a comparison
The codes have different starting dates and works
The codes are independent
=> inter-code homonyms are possible, allowed, and common

57. Table 1. Inter-Code Generic homonyms
Botanical genus names
homonyms in Zool. record
Total
64,419
8,784 (13.6%)
in common use
28,041
3,554 (12.7%)
Bacteriological genus names
Homonyms in Zool. Record
Homonyms in ING (Botanical)
Homonyms in both
739
50 (6.8%)
29 (3.9%) 15
701
48 (6.9%)
27 (3.9%) 14

58. Examples of genus + species homonoms:
Poria cocos: Coleoptera and Fungus;
Pieris japonica: butterfly and plant;
Culcita novaeguineae: seastar, and Culcita novae-guineae: fern

59. The different codes: a comparison
Principle of co-ordination:
in zoological nomenclature, not in botanical;

60. The different codes: a comparison
Principle of co-ordination:
Names established at any rank within the F/G/S groups are deemed established at any rank within the group
Family-group: Super-,Family, sub-, Tribus, sub-
Genus-group: Genus, sub-
Species-group: Species, sub-

61. The different codes: a comparison
Principle of co-ordination
Tautonyms (Bison bison,...)
allowed in zoology;

62. The different codes: a comparison
Principle of co-ordination
Tautonyms
Latin diagnosis
required in botanical nomenclature

63. The different codes: a comparison
Principle of co-ordination
Tautonyms
Latin diagnosis
Application & different standardised endings

64. Table 2: Standardized endings for names of taxa
Rank :
Zoological
Botanical
Bacteriological
phylum/divisio *
- phyta/-mycota1
classis
- opsida/-mycetes1/ -phyceae²
subclassis
- idea/-mycetidae1/-phycidae2
superordo
- anae
ordo
- ales
subordo
- ineae
superfamily
- oidea
(not used)
family
- idea
- aceae
subfamily
- inae
- oideae
tribus
- ini
- eae
subtribus
- ina
1: for fungi; ²: for algae

65. Interesting websites
International Code of Botanical Nomenclature :
International Commission and Code on Zoological Nomenclature :
Index Nominum Genericorum (names of genera of plants, fungi and algae :
List with suprageneric names :
Directory of International Registration Authorities (esp. for cultivars) :

66. Did I mention these ones?
Games with letters/statistics:
Aa Baker, 1940 (mollusk)
Aaadonta Solem, 1976 (endodontoid slug)
Cavaticovelia aaa Gagne, 1975 (Hawaiian bug)
Aragara Walker, 1860 (fly; longest palindrome)
Ia io Thomas, 1902 (bat; shortest binomen)
Gammaracanthuskytodermogammarus loricatobaicalensis Dybowski, 1926 (amphipod; the longest binomen)
Zyzzyxdonta Solem, 1976 (endodontoid slug,
with opposite features of Aaadonta)
Zyzzyzus Stechow, 1921 (Coelenterata)

67. Thank you for your attention Merci pour votre attention