A SIGNIFICANT RANGE EXTENSION FOR THE TEXAS MAP TURTLE (GRAPTEMYS VERSA) AND THE INERTIA OF AN INCOMPLETE LITERATURE

作者：Lindeman Peter V^*

来源：Herpetological Conservation and Biology, 2014, 9(2): 334-341.

• Balcones Escarpment
• Colorado River
• Edwards Plateau
• range limits
• relative abundance
• Texas

Defining the limits of a species' geographic distribution is fundamental to research in biogeography, ecology, and conservation biology. The Texas Map Turtle, Graptemys versa, is endemic to the Colorado River drainage in central Texas but has been incorrectly reported by several sources to be restricted to the part of the Colorado drainage located on the Edwards Plateau, northwest of the fault lines of the Balcones Escarpment. I conducted visual surveys of basking turtles, vouchered with photographs, which demonstrate that even statements that the species occurs mainly above the Balcones Escarpment are incorrect. I observed higher numbers and higher relative abundances within basking turtle assemblages throughout the five counties downstream of the Edwards Plateau, in over 400 river km of the Colorado, and an abundant population was observed just 48 river km from the river's mouth in coastal Matagorda County. Literature statements regarding restricted limits of freshwater turtle geographic ranges should be critically appraised for their accuracy. Surveys that are conducted beyond published range limits must also be detailed not just for new records but also for negative results, in order to enable future workers to properly evaluate statements about range limits.

• 出版日期2014-10