Classification is used to group together plants and animals which are closely related. This
helps to organise our knowledge of the great diversity of living things. The
system used in biology is composed of a hierarchical or nested set of categories,
starting with the broad, general groupings and progressing through a series
of categories to the smallest group, a single species. The highest group is
the Kingdom and all animals belong to the same kingdom, Animalia. Below kingdom
is Phylum, followed by Class, then Order, Family, Genus and finally Species.
For example the common meat ant would have the following classification:
In addition to these major categories, several additional categories are used
which lie between them. The more important of these include Subfamily, Tribe,
Subgenus and Subspecies. All ants belong to a single family, Formicidae. Within
the ants, only three categories are commonly used, subfamily, genus and species.
Subfamily is the largest grouping, and determining which subfamily a specimen
belongs to is the first step in any identification (see
Key
to the Subfamilies).
There are 16 living subfamilies world-wide (see list at right) , with ten
of these occurring in Australia (see
List of
Subfamilies). Of these ten subfamilies, five (
Dolichoderinae,
Formicinae,
Myrmeciinae,
Myrmicinae and
Ponerinae)
are very common and are encountered regularly in most areas. The remaining
subfamilies vary from fairly common in areas were they occur to very rare
and seldom seen. Most ants can be placed to subfamily with little difficulty,
and with practice the subfamily key can be bypassed so that identification
of most specimens will begin with keys to genera.
The category below subfamily is genus. (Tribe is between subfamily and genus but
is only used in selected groups.) There are about 300 genera of ants world-wide
and 101 of these are found in Australia (see
List
of Genera). The genus is the fundamental identification unit in ants and
most ants can be identified to genus with minimal difficulty (especially when
compared with species-level identifications). Additionally, much of the current
information about Australian ants is of a general nature and is applicable
to most members of a genus. Thus identifying ants to genus-level is a manageable
task which will provide considerable information on the biology and ecology
of the specimen. The names of genera are always printed in italics or are
underlined when hand written.
The final level of classification is the species. To reliably determine the species
identity of a specimen either a recent, detailed taxonomic revision is necessary,
or reliably determined material must be available for comparison. In many
cases species can be determined only by sending specimens to one of the larger
collections so direct comparisons can be made with previously determined material.
However, even in these cases the identification of many species will be very
difficult or impossible because most groups of Australian ants have yet to
be studied in detail.
As with generic names, the names of species are always printed in italics or
are underlined when hand written. In addition, the name of the person originally
describing the species is also included and sometimes the year in which the
species was described as well. For example, the name of the common meat ant
of south-eastern Australia is
Iridomyrmex purpureus (Smith) or
Iridomyrmex
purpureus (Smith, 1858), where
Iridomyrmex is the genus or generic
name,
purpureus the species or specific name, Smith the author of this
name and 1858 the year the name was published. In this particular case Smith’s
name is placed in parentheses to indicate that his species is no longer in
the same genus that he originally described it in. This is because Smith had
places his species in the genus
Formica (as
Formica purpurea
Smith) and it was subsequently moved to the genus
Iridomyrmex.