How to … Tell if my new species is already named
A species is already named if the type of an existing validly published species name falls within the circumscription of the intended new species. Note that the name may be an old one that has not been used for many years, or it may never have been taken up (here's an example), or it may be in a different genus. So you need to be confident that there is no other name that could be a validly published, earlier name for your species. Follow these steps to check:
Make or obtain a list of all species names that could potentially be relevant to your new species (these may include species in related genera, and some may be names that have been synonyms of other names for many years).
Cross off the list all names that clearly apply to other species (that is, are accepted names for other species, or are known and assigned synonyms for other species).
For any names that remain on the list, check their type specimens to ensure that the type does not fall within the circumscription of your new species.
If no potential names remain after all names on the list have been checked, you can be reasonably confident that your species is currently un-named.
For more information, see Chapter 5 How to publish a new name in The Code Decoded.