differentia specifica , auch: specific difference

He was the first to use consistently the uniformly composed species names that consisted of a generic name and a many-worded diagnostic phrase differentia specifica.

If there are more than one species belonging to the genus, their names should consist of the generic name followed by differentia specifica (a brief diagnostic phrase).

Before Linnaeus, long many-worded names (composed of a generic name and a differentia specifica) had been used, but as these names gave a description of the species, they were not fixed.

In the genera containing more than one species the first species was named with generic name only, while the second, etc. were named with a combination of the generic name and a modifier (differentia specifica).

His nomenclature differed from that by Joseph Pitton de Tournefort because he did not use differentia specifica with the first plant of a genus, adding differentiae only to the second and subsequent plant species.