Page last updated
28 December 2007

The Accumulation of Freshwater Mussels Names

The taxonomy of freshwater mussels is complicated by its particular history. One particularly problematic aspect of unionoid taxonomy is the terrific rate at which mussels were named and described during the 19th century. The figure below shows the accumulation of species-group level nomina from Linnaeus (1758) to the last global revision of freshwater mussel species, Haas (1969).

The green dashed line represents the yearly accumulation of the available names listed in Haas (1969). The dashed gray line represents how many species have been treated as valid over the years, based on the global treatments of Linnaeus (1758), Lea (1836, 1870), Simpson (1900, 1914) and Haas (1969). Those individual studies are represented on the chart by six yellow stars.

From Haas (1969), we count 4178 described species (plus 115 unavailable names). He synonymized those names down to 837 valid species (1037 species and subspecies). That is an average synonymy rate, based on Haas's data, of 5:1! However, relative to Simpson (1900, 1914), Haas would be considered somewhat of a lumper.

Based on the data presented by Haas (1969), we can also see that these synonyms are not randomly distributed throughout the taxonomy of freshwater mussels. Certain mussel species have received the bulk the attention, and their over-naming occurred through the action of a relatively small number of practitioners.

References

• Haas, F. 1969. Superfamilia Unionacea. Das Tierreich (Berlin) 88. 663 pp.
• Lea, I. 1836. A Synopsis of the Family of Naiades. Cary, Lea and Blanchard, Philadelphia, Pennsylvania. 59 pp.
• Lea, I. 1870. A Synopsis of the Family Unionidae. Fourth Edition, very greatly enlarged and improved. Henry C. Lea, Philadelphia, Pennsylvania. 184 pp.
• Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum characteribus, Differentiis, Synonomis, Locis. Tmus I. Editio Decima, Reformata. Holmiae, Impensis Direct. Laurentii Savlii. 823 pp.
• Simpson, C.T. 1900. Synopsis of the naiades, or pearly fresh-water mussels. Proceedings of the United States National Museum 22: 501-1044.
• Simpson, C.T. 1914. A descriptive catalogue of the naiades, or pearly fresh-water mussels. Parts I-III. Bryant Walker, Detroit, Michigan. 1540 pp.