Eurytemora carolleeae in the Laurentian Great Lakes revealed by phylogenetic and morphological analysis

In the Laurentian Great Lakes, specimens of Eurytemora have been reported as E. affinis since its invasion in the late 1950s. During an intensive collection of aquatic invertebrates for morphological and molecular identification in Western Lake Erie in 2012-2013, several specimens of Eurytemora were collected. Analysis of these specimens identified them as the recently described species E. carolleeae Alekseev and Souissi 2011. This result led us to assess E. carolleeae's identifying features, geographic distribution and historical presence in the Laurentian Great Lakes in view of its recent description in 2011. Cytochrome oxidase I (COI) DNA sequences of Eurytemora specimens were identified as closer (2 - 4% different) to recently described E. carolleeae than to most Eurytemora affinis sequences (14% different). Eurytemora from other areas of the Great Lakes and from North American rivers as far west as South Dakota (Missouri River) and east to Delaware (Christina River) also keyed to E. carolleeae. Morphological analysis of archival specimens from 1962 and from all the Great Lakes were identified as E. carolleeae. Additionally, Eurytemora drawings in previous publications from studies in the Holarctic region were reassessed to determine if these specimens were E. carolleeae. Additional morphological characters that may distinguish the North American E. carolleeae from other taxa are also described. We conclude that E. carolleeae is the correct name for the species of Eurytemora that has inhabited the Great Lakes since its invasion, as established by both morphological and COI sequence comparisons to reference keys and sequence databases in present and archival specimens.