RANGE EXTENSION OF THE FRESHWATER MUSSEL POTAMILUS PURPURATUS (BIVALVIA: UNIONIDAE) IN TEXAS

摘要

The freshwater bivalve Potamilus purpuratus is a large, distinctive unionid which occurs throughout much of the central and lower Mississippi River Valley (Cummings & Mayer 1993; Vidrine 1993). It is also known to occur in tributaries of the Gulf of Mexico east and west of the Mississippi River (Strecker 1931; Vidrine 1993). In Texas, this species occurs from the Red River drainage southwest into the Guadalupe/San Antonio River drainage (Howells et al. 1996). Strecker (1931) did not report P. purpuratus from the Nueces or Frio rivers and Murray (1978) did not find it in a survey of Lake Corpus Christi on the lower Nueces River. Previous reports by Strecker (1931) of this species from the Devils River near its confluence with the Rio Grande were found to represent misidentified specimens (R. Neck & C. Boone, pers. comm.) of the Tampico pearlymussel Cyrtonaias tampicoensis. Metcalf (1982) did not find this species represented in the fossil assemblages of the central Rio Grande and Neck & Metcalf (1988) did not report it from the lower Rio Grande downstream from Falcon Reservoir.