Isaac Lea's (1792–1886) Substitutions and Other Modifications of His Own Names of Molluscan Species

The American conchologist Isaac Lea had a long and productive career during which he introduced more than 1,800 names of molluscan species between 1827 and 1874, the majority North American land and freshwater species. His idiosyncratic way of publishing, by describing new taxa multiple times in duplicated and variously modified journal papers as well as in retitled collections of extracts, has led to considerable difficulties in determining accurate dates of his original descriptions. He considered the reading and presentation of a manuscript before a “learned society” as the date of its original publication and therefore his own recorded dates must be approached with caution. The problem of interpreting Lea's names was compounded by the fact that Lea frequently modified his own new taxonomic names in his subsequent publications, and often without providing justification for the change. The various name versions were inconsistently applied by subsequent authors. The current paper analyses Lea's substitutions and other modifications of his own names of molluscan species and discusses 131 of his publications in this context, for which attempts at precise dating were made. The status of these “replacements” of Lea's taxonomic names were evaluated under the current ICZN Code (1999). A few additional cases of changes of Lea's names by other authors are included; these are instances in which Lea had missed a primary homonym or a secondary homonym was discovered later. While some of the names here discussed are currently resting in synonymy, others are of greater current relevance as they are in use as valid names for taxa of conservation/management concern, including IUCN and U.S.-federally listed species. The following 98 discussions of often-complex name changes involve 348 species-group names and their subsequent spellings, 231 of which were introduced by Lea. Based on their current taxonomic status, the names belong to 4 bivalve and 11 gastropod families, with the vast majority concentrated in Unionidae and Pleuroceridae. Under the current ICZN Code, the investigated changes fall into many different categories, which impacts their nomenclatural availability: 35 names changed by Lea (plus 6 by other authors) are interpreted as substitute names for junior primary homonyms, 7 of which were unnecessary; 1 name (plus 6 by others) as substitute names for junior secondary homonyms, 1 of which was unnecessary; 13 names as justified emendations; 10 names (plus 1 by another) as unjustified emendations that have not entered prevailing usage; 1 name determined by his first reviser action; 37 names (plus many by others) as incorrect subsequent spellings that are not in prevailing usage; and 1 incorrect subsequent spelling that is shown to be in prevailing usage and thus considered a correct original spelling. The concept of “prevailing usage,” ill-defined under the current (1999) ICZN Code, is addressed in this context. The following names in current use are corrected as follows: Helix balasteriana I. Lea, 1840 (taxon inquirendum, ?Dyakiidae), Lioplax cyclostomatiformis (I. Lea, 1844), Diplodon demararaensis (I. Lea, 1859), Iheringella isocardiodes I. Lea, 1856, Dilatata brongniartiana (I. Lea, 1843), Elliptio nasutidus (I. Lea, 1863), Elliptio pullata (I. Lea, 1857), Pleurocera picta (I. Lea, 1841) [instead of P. curta (Haldeman, 1841), which is preoccupied] and Beringiana youconensis (I. Lea, 1847); many others are confirmed in their recently applied spellings. This work serves as an example that the basic endeavor of summarizing available and valid names from the published literature is not always a straightforward task.