A guide to naming taxa.

Binomina, a.k.a. binomial names, scientific names, or Latin names, are unique, universal two-word names assigned to differentiate between taxa. Although focused on binomina, this entry covers the naming of all taxonomic ranks.

Generic Name

The generic name is the first part of the binomial name: the Homo in Homo sapiens, the T. in T. rex. It indicates which genus an organism is in. In inventing one, in particular for polytypic genera, the main thing to consider is the evolutionary history of the organism (or whichever other characteristic it's being classified by, if you're choosing to do so paraphyletically). Which of the traits you're defining it by are more likely to have come in earlier, such that they would be present in sister species too?
For example, consider the binomina Pinus nigra (from Latin pinus 'pine' and niger 'black') the black pine, and Pinus densiflora (from Latin pinus 'pine' and densus 'dense' + floris 'flower') the Japanese red pine. The shared generic name, Pinus, indicates their shared status as pine trees, a characteristic that arose before -and is more obvious than- the dark bark of the black pine, or the thickly clustered needles of the Japanese red.

This is, of course, harder if your genus is monotypic, and far from the only way to name one. Generic names also sometimes derive from things like mythology (e.g. the chimpanzee genus Pan, after the Ancient Greek god), historical figures (e.g. the mountain bell genus Darwinia, after Charles Darwin), the location of discovery (like the ape genus Anadoluvius, after Anatolia), or anagrams of existing genera, especially when there is some similarity between them (e.g. the monocot genus Muilla, an anagram of Allium).

Specific Name

The latter part of a binomen is the specific name. Where generic names distinguish a species from members of other genera, a specific name distinguishes a species from other members of the same genus. Here, think of recent evolutionary adaptations or superficial characteristics that might distinguish an individual species. Specific names frequently derive from the color, location, or discoverer of the species. Remember that the number of species in a genus can range from one to over 3000 - the degree of distinction should be based solely on empirical differences.

Note: Botany does not allow specific names that are identical to the generic name as zoology does. (e.g. Gorilla gorilla).

Subspecific Name

Generally, when a species is split into subspecies, whichever subspecies the type specimen is determined to be in is named after the species itself. For instance, when the tiger (Panthera tigris) was split into subspecies P. tigris tigris, P. tigris altaica, P. tigris amoyensis and P. tigris sumatrae, the tiger type specimen was determined to be a Bengal tiger and the Bengal tiger subspecies inhereted the specific name.
There are, however, exceptions to this rule: the Napoleon spider, Synema globosum, splits only into S. g. clarum, S. g. flavum, and S. g. pulchellum. This is rare, though, and generally explicable either by the absence of a type specimen or outdated naming conventions at the time of the classification.

Note: Modern taxonomy doesn't allow subspecies distinguished solely by superficial characteristics and only sufficient genetic distinction warrants their designation.

Other taxa

Zoology

The names of the following taxa must end in particular suffixes:

• Superfamily: -oidea (ex: Hominoidea)
• Family: -idae (ex: Hominidae)
• Tribe: -ini (ex: Hominini)
• Subtribe: -ina (ex: Hominina)

Botany

The names of the following taxa must end in particular suffixes:

• Division/Phylum: -phyta (ex: Magnoliophyta)
• Subdivision/Subphylum: -phytina (ex: Spermatophytina)
• Class: -opsida (plants; ex: Magnoliopsida), -phyceae (algae)
• Subclass: -idae (plants; ex: Rosidae), -phycidae (algae)
• Order: -ales (ex: Rosales)
• Suborder: -ineae (ex: Rosineae)
• Family: -aceae (ex: Rosaceae)
• Subfamily: -oideae (ex: Rosoideae)
• Tribe: -eae (ex: Roseae)
• Subtribe: -inae (ex: Rosinae)

Mycology

The names of the following taxa must end in particular suffixes:

• Division/Phylum: -mycota
• Subdivision/Subfamily: -mycotina
• Class: -mycetes
• Subclass: -mycetidae

Senses

Because of the fluid and gradual nature of evolution (and the fact that taxa are ultimately arbitrary, at least to some extent) the exact ranges attached to binomina may vary. To avoid ambiguity, binomina are often further specified by sense. The most common of these are sensu stricto ('in the narrow sense'; ex: Homo erectus sensu stricto') and sensu lato ('in the broad sense'; ex: Homo erectus sensu lato) These may be abbreviated as s.s. and s.l. respectively. Senses may also be named as described or applied in particular papers (ex: H. erectus sensu Howell, 1960, abbreviated H. erectus s. Howell, 1960).

Latin Grammar

Although binomina are often derived from other languages like Ancient Greek, and a push has recently begun to include modern languages like Malaysian and Mandarin, all binomial names must be Romanized and are subject to Latin grammar.

Declension

Adjectives used as specific names must have a grammatical gender, number and case in agreement with the genus name. Disgregarding linguistic details, look under whichever table has the declension paradigm of your generic name and add the matching suffix under the declension paradigm of your specific name to your specific name. Ommit accents, as they are relevant only to pronounciation.

First Declension Paradigm (-a)

Second Declension Paradigm (-o)

Third Declension Paradigm (Consonants)

Formatting

1. Generic and specific names are always italicized and in sentence case (Felis catus, not Felis Catus).
   In botany, it's generaly preferred to italicize all taxon names.
2. Abbreviation of generic names (F. catus) is best avoided if the full word hasn't already been spelled out prior in the text.
   The same applies to specific name if subspecies is specified (F. c. catus), and so on for lower ranks. This does not commonly apply to senses.
3. Subspecific ranks are often specified, particularly in botany (Saxifraga aizoon var. aizoon subvar. brefifolia f. multicaulis subf. surculosa). Abbreviations are not italicized. The appropriate abbreviations for zoological and botanical subspecific ranks are:
   • Species: sp.
   • Subspecies: subsp.
   • Variety: var.
   • Subvariety: subvar.
   • Form: f.
   • Subform: subf.
4. The original descriptor and year of description of a species is sometimes specified (Hydrangea aborescens Linnaeus, 1753).