Type concept

The ICN's second principle requires every scientific name to be tied to a physical specimen or illustration called the nomenclatural type (e.g. a herbarium sheet for a vascular plant) - this is the objective anchor that fixes what a name actually refers to.

• Holotype: the single specimen or illustration the author originally cited in the protologue; the definitive reference for the name's identity, and its citation/submission is one criterion for valid publication.
• Isotype: a duplicate of the holotype, collected from the same population by the same person on the same date with the same field number - reliable duplicates often distributed to herbaria in different regions.
• Lectotype: a specimen chosen from the ORIGINAL material to serve as the type when no holotype was designated at publication, or when the holotype is missing/destroyed.
• Syntype: any one of several specimens the author cited together in the protologue when no holotype was designated.
• Neotype: a specimen chosen from NON-original material, only when the true original material is missing or destroyed. …