Representing Taxon relationships in a Checklist

[LordFlashmeow]

In a Taxon Checklist for ICZN nomenclature, the originalNameUsage refers to the original combination, as the first usage of the protonym.

If a taxon is a secondary homonym, the definition seems conflicting to me. As a subsequent combination, should originalNameUsage point to the original combination, or should it refer to the senior homonym that it conflicts with?

Additionally, how is acceptedNameUsage used in this scenario? Should it refer to the replacement name for the homonym, or should it refer to itself as the most current name? The comment says it’s for when the scientificName is considered “to be a synonym or misapplied name”. Is the homonym’s replacement name considered a synonym?

[deepreef]

My interpretation of originalNameUsage in this case is that it should represent the original combination of the secondary homonym, not the senior homonym. DwC Taxon terms are not sufficient to confer both nomenclatural and taxonomic information, so statements about secondary homonymy aren't directly supported. This is why there is a fair bit of effort focused on the Taxon Names and Concepts Interest Group to allow more robust exchange of this kind of taxonomic and nomenclatural information.

In the case of a secondary homonym, I would use acceptedNameUsage to represent whatever name is deemed by the content provider or represented Reference to represent the "correct" scientific name. I interpret the word "correct" in this context to mean both nomenclaturally correct name (replacement names, objective senior synonyms, correct original spelling, etc.) and the taxonomically correct name (subjective synonymy, classification including genus placement, etc.).

For example, assuming we have:

Aus bus Smith 1850
Xus bus Jones 1900
Aus bus (Jones 1900)
Aus cus Pyle 2000 (replacement name for Jones' bus)

The record for Aus bus Smith 1850 would have the same value ("Aus bus Smith 1850") for scientificName, originalNameUsage and acceptedNameUsage (assuming the name is still regarded by the Reference/Provider as representing a valid species, within the genus Aus).

The record for Aus bus Smith 1850 would have these values:
scientificName: Aus bus (Jones 1900)
originalNameUsage: Xus bus Jones 1900
acceptedNameUsage: Aus cus Pyle 2000

Again, this is how I would represent it. DarwinCore terms do not define it with this level of precision (hence the ongoing work of the Taxon Names and Concepts Interest Group).