Kevin S. Cummings and Christine A. Mayer
Illinois Natural History Survey
1816 South Oak Street
Champaign, IL 61820
The freshwater mussel fauna of South America is very poorly known. Although studied since 1792, few areas have been adequately sampled and much of the continent remains unstudied. Ortmann published a monograph on South American naiads in 1921 but made no references to the fauna of the Rio Orinoco, one of the largest drainages in the continent. H.B. Baker was the first to monograph the land and freshwater Mollusca of Venezuela which he published in six parts from 1923 to 1930. Even after Baker’s work, much of Venezuela remained unstudied.
Venezuela is located in the northeastern portion of South America between 1 and 12 degrees north latitude and 60 and 73 west longitude. The country is bordered on the north and northeast by the Carribean and Atlantic Ocean, on the west by the Colombia, on the south by the dense jungles of Amazonas and Brazil, and on the east by Guyana. There are four principal drainages: The Maracaibo Basin in the northwest, the direct tributaries along the northern coast, the large Orinoco River system and the Essequibo drainage in the east. The country is bisected by the Andes and in the interior is a large rolling periodically flooded grassland called the Llanos.
We examined all available specimens in North American museums and found fewer than 15 collection sites from the Rio Orinoco drainage, the largest watershed in Venezuela. Field work conducted throughout Venezuela over the past nine years has added over 65 new sites and thousands of additional specimens which has helped to clarify some distributional and taxonomic problems. Examination of the literature and museum specimens, combined with field studies, brings the total number of described species recorded from Venezuela to 19. The family Hyriidae is represented by six species in the genera Castalia (2), Diplodon (2), Paxyodon (1), and Triplodon (1). The family Mycetopodidae is represented by thirteen species in the genera Anodontites (9),Lamproscapha (1), Mycetopoda (2), and Tamsiella (1). Preliminary study of recent collections suggests the possibility of four new species. The four undescribed taxa include one species each in Castalia and Diplodon and two in Anodontites. Because of the size and remoteness of the country and the wide variety of habitats present, additional collecting will undoubtedly add new species to and expand our knowledge of the freshwater bivalve fauna of Venezuela.
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