Abstract

Speciation as a consequence of lineage reticulation is not uncommon. A taxonomic and nomenclatural issue arises when a putative hybrid becomes established and is, therefore, in contention for species recognition. While giving a unique name to a hybrid may be acceptable under the codes that govern nomenclature, this does not address issue of whether it constitutes a valid species. We suggest that there are two classes of hybrids. The first type of hybrid is episodic and not consistently present through time and, although such taxa may have a definition and name, we contend that they should not be considered species. The second type of hybrid is one that is indicative of a stable and continuing reticulation, where its definition and name identify and validate a reference point to enhance evolutionary explanation. We highlight that a conflict with the codes that govern functional nomenclature does not occur if the original author did not identify the taxon they were describing as a hybrid. In spatiotemporally stable populations, we argue against the retrospective invalidation of an existing species based on gained insights into putative hybrid ancestry. Instead, hybrid ancestry should be treated as bringing casual understating to the evolution of an organism. In contrast, arguing for hybrid ancestry under the current rules at the time of describing a taxon is seen as presenting an argument for invalidation if the rules are applied in the strictest sense. Furthermore, we argue that the collapse of infrafamiliar taxa based on hybrid ancestry reduces the explanatory potential of the nomenclature. We present a case study in which names now attributed to putative hybrids within Strombidae are considered for validation.

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