Species inquirenda
[2] The use of the term in English-language biological literature dates back to at least the early nineteenth century.[3] The term taxon inquirendum is broader in meaning and refers to an incompletely defined taxon of which the taxonomic validity is uncertain or disputed by different experts or is impossible to identify the taxon.Species names may remain unplaced if there is no accepted species in a genus in which it can be placed, or if the type material for the species is not known to exist, is insufficient to establish a clear identity, or has not been studied by experts in the group in order to properly place it.[4] Nomenclatural instability refers to the phenomenon where there is disagreement or lack of consensus regarding the naming of a species, which can lead to multiple proposed names for the same species.Synonymy: when different names are proposed for the same species, they become synonyms, which can complicate classification and identification.