Recent Eupera (Pelecypoda; Sphaeriidae) in the United States

Abstract

The taxonomic history of the sphaeriid clam genus Eupera is reviewed, and the morphological relationships of Eupera to other genera are examined. The presence of separate siphons, byssal threads, and the unusual marsupial development of the embryos require the establishment of a new subfamily, Euperinae. Eupera singleyi (Pilsbry) is synonymized under E. cubensis (Prime) which is redescribed in detail. The specific distribution of E. cubensis, the single Recent member of the genus in the Nearctic Region, is in the Atlantic and Gulf 'Coastal Plains from North Carolina to Mexico, and the Valley and Ridge Province in central Alabama. IN1TRODUCTION Most published information on the ovoviviparous and hermaphroditic freshwater clam family Sphaeriidae concerns the taxonomy, life history, and distribution of the genera Sphaerium Scopoli, Musculium Link (frequently considered congeneric with, or a subgenus of, Sphaerium), and Pisidium C. Pfeiffer. Aside from the original descriptions, little is known of the highly localized monotypic genera Byssanodonta d'Orbigny (Rio Parana, Provinz Corrientes, Argentina) and Pseudocorbicula Dautzenberg (Lake Victoria, Kenya). Eupera Bourguignat is widespread in the Ethiopian and Neotropical Regions with one species, E. cubensis (Prime), occurring in North America. The present report is concerned with the systematics and distribution of E. cubensis in the Nearctic Region. The life history and anatomy of this species will serve as the subject of a later report. I am indebted to F. G. Thompson of the University of Miami Department of Zoology, J. C. Dickinson of the Florida State Museum, H. Rehder and J. P. E. Morrison of the U.S. National Museum, and H. van der Schalie of the University of Michigan Museum of Zoology for their kindnesses in providing material for examination. Special appreciation is extended to W. J. Clench of Harvard's Museum of Comparative Zoology (MCZ) and to R. T. Abbott of the Academy of Natural Sciences of Philadelphia (ANSP) for the loan of Prime's cotypes of Sphaerium cubense and Pilsbry's holotype and paratypes of Sphaerium (Limosina) singleyi, respectively. TAXONOMIC HISTORY Bourguignat (1854a) divided Pisidium C. Pfeiffer (1821) into two large series (subgenera?): (1) Pera Leach (1852) in which the ligament is on the shortest side of the beaks, and (2) Eupera I This investigation was supported (in part) by research grant 5 TI AI 41-05 from the National Institute of Allergy and Infectious Diseases, U.S. Public Health Service.