Abstract
According to the International Code of Zoological Nomenclature (ICZN, 2012: art 57.2), identical species-group names established for different nominal taxa, when originally combined with the same generic name, are primary homonyms. The junior name becomes therefore permanently invalid, except in few selected cases, which however are not met in the two species we will deal with below. The Principle of Priority requires that if a name in use for a taxon is found to be unavailable or invalid, it must be replaced by the next oldest available name from among its synonyms, including the names of the contained taxa of the same group (e.g., subgenera within genera), if that name is not itself invalid. If the rejected name has no potentially valid synonym a new substitute name must be established in its place (ICZN, 2012: art 23.3.5, art. 60). This is the case of two recently described extant molluscan taxa, whose specific names are preoccupied by homonymous fossil taxa.
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