The identification keys - or dichotomous keys - are tools used in the process of identification of an unknown organism, in order to ascribe it to a given taxon.
Such paths take into account some morphological characters, by providing mutually exclusive options.
Posterior angles of the head acute
Posterior angles of the head more obtuse
Overall color of the abdomen reddish
Overall color of the abdomen blue or green, but not red
In the example, 1 is the first morphological character, with two opposing or exclusive options (acute or obtuse angles). The choice of the first option leads to the path 2, while choosing the second option leads to the path 7: 2 and 7 are therefore intended as "proceed to the character number 2" and "jump to the character number 7". The character that follows in the key, 2, has a new dichotomy. Such dichotomy, in the case of the first option, will take you directly to the identification of the organism as belonging to a hypothetical species-X. In the case of the second option, on the contrary, you need to continue to the character number 3, and so on.
Thus, inspecting the morphology of the specimen under the microscope with the dichotomous key, you build a path in order to give your specimen a well-defined name from a range of possibilities and thus attain its identification.
The process of identification through keys can be hierarchical, that is is used to proceed from broad systematic categories to smaller ones, eg. from a subfamily to a tribe, then to a genus, then to a species group. Or can operate on one taxonomic level, as that for the identification of a species among all possible species belonging to the same genus.
Il processo di identificazione tramite chiavi richiede capacità interpretative notevoli ed è generalmente appannaggio dello specialista, che, fra l'altro, ha esperienza in ambito morfologico-sistematico e dispone di una collezione con esemplari e specie di confronto.
The process of identification through such keys require considerable interpretive skills, and is generally a prerogative of the specialist. The specialist, among other features, has experience with systematics and morphology and has a reference collection of specimens and species.
Please note: the key is currently available in Italian language only.
For citation purposes
Agnoli G.L. & Rosa P., Chrysis.net website, interim version 24-Apr-2012 , URL: http://www.chrysis.net/.