New Turtle Species Out of its Shell in U.S.
|The Pearl Map Turtle, so named for the map-like pattern of light colored lines often seen on its shell, is found in the Pearl River in Louisiana and Mississippi. Courtesy of Cris Hagen, University of Georgia, Savannah River Ecology Laboratory|
When scientists announce the discovery of a new animal species, we often imagine exotic, difficult to reach locations — the untouched shore of a distant island, the forests of the rain-drenched Amazon or the darkest depths of the Arctic Ocean. But the recent announcement of a new species of turtle in the southeastern United States proves that, even in a country considered to be well-explored, perhaps more awaits discovery. In June 2010, Jeff Lovich, Northern Arizona University (NAU) adjunct faculty member in biology, and Josh Ennen, NAU affiliate, published the discovery of a new species of turtle in Chelonian Conservation and Biology International Journal of Turtle and Tortoise Research.
Found in the Pearl River, which flows through Mississippi and Louisiana before it meets the Gulf of Mexico, the newly named Pearl Map Turtle, or Graptemys pearlensis, had been mistaken for a turtle native to the neighboring Pascagoula River. Ennen found it odd that the Pascagoula Map Turtle was found in both rivers and wanted to further investigate.
Ennen was completing his dissertation at University of Southern Mississippi when he decided to take a closer look at the inhabitants of the two rivers. His research led him to Lovich, who had found, described and named the last turtle species in the same region in 1992.
“I was familiar with Jeff’s work when questions started coming up,” Ennen said. “Based on the genetics, morphology and geographic isolation, I was considering classifying the turtles as distinct population segments when I decided to contact Jeff.”
Lovich, a research ecologist with U.S. Geological Survey (USGS)’s Colorado Plateau Station at NAU, shared his findings and insight as the scientists built their case for classification of the new turtle species. His access to geologic and geographic data with the USGS assisted in their developing theory that the turtles had evolved into separate species.
“You’d expect to see similar aquatic species in these rivers due to their proximity,” Lovich said. “However, with sea level changes associated with glacial and interglacial periods in the past, animals in these rivers were periodically separated for tens of thousands to millions of years.”
Ennen and Lovich observed pattern variations between turtles in the two rivers, and examining their DNA verified that the turtle endemic to each river was a different species.
The announcement of the Pearl Map Turtle, “Genetic and morphological variation between populations of the Pascagoula Map Turtle (Graptemys gibbonsi) in the Pearl and Pascagoula Rivers with description of a new species,” brings the number of native turtle species in the United States to 57, including six in Arizona, with approximately 320 species documented worldwide.