Neotype is validly designated when :

Question

Accepted Answer

The correct option is 4: All the original material is lost

The valid designation of a Neotype is one of the most rigorously controlled actions in taxonomic nomenclature, governed by the International Code of Zoological Nomenclature (ICZN) and the International Code of Nomenclature for algae, fungi, and plants (ICN). A Neotype is a single specimen designated as the type specimen only when *all* of the original type material associated with the species name is conclusively known to be permanently lost, destroyed, or unidentifiable. This original material, collectively called the 'type series,' includes the Holotype, Isotypes, Syntypes, Lectotype, and Paratypes. The Neotype designation is considered a "last resort" measure to provide a clear, unambiguous reference point for the species name when the scientific anchor—the original material—has been entirely removed from existence. If even one specimen from the original type series remains and can be found, a Neotype cannot be validly designated.

The incorrect option is 1: Syntype is not available

A Syntype is one of two or more specimens cited by the original author when no Holotype was explicitly designated. While the non-availability of Syntypes reduces the original material, it does not confirm the complete loss of the entire type series. A Holotype (if one was designated initially) or other original specimens like Isotypes or Paratypes might still be intact and available in collections. According to the rules, a Neotype can only be established after it has been demonstrated that *none* of the specimens constituting the name-bearing type, or any other original material, can be traced. The mere absence of a Syntype is an insufficient criterion to proceed with the designation of a Neotype.

The incorrect option is 2: Isotype is available

An Isotype is defined as a duplicate specimen of the Holotype collected at the same time, from the same place, and by the same collector. The *availability* of an Isotype directly contradicts the fundamental requirement for designating a Neotype. If the Holotype is lost, the presence of an Isotype means that original material still exists, which must then be designated as the new name-bearing type, usually as a Lectotype. The very definition of a Neotype—a type chosen when *no* original material remains—means that the availability of an Isotype immediately invalidates any proposed Neotype designation. Therefore, this option describes a scenario where a Neotype is expressly forbidden by the rules of nomenclature.

The incorrect option is 3: Holotype is lost

The Holotype is the single most important specimen, designated by the original author to physically embody the scientific name. The loss of the Holotype is a necessary condition for further action, but it is not a sufficient condition for selecting a Neotype. The nomenclature codes mandate that if the Holotype is lost, a search must first be conducted for other original material, such as Isotypes, Syntypes, and Paratypes. If any of these original specimens are found, one of them must be designated as a Lectotype to replace the Holotype. The Neotype only comes into play as a final option once the existence of *all* other original specimens has been definitively ruled out.