Distinguishing among species of larvae of the dragonfly genus Tramea historically has been problematic, largely due to conflicting characterizations of the larvae of T. lacerata Hagen and T. onusta Hagen (Odonata: Libellulidae) in the literature. The various systematic treatments usually focused on relative lengths of morphological characters to distinguish the species, but often contradicted one another and themselves as to what the diagnostic values actually were. We traced much of the confusion back to errors in the original larval description of T. onusta. We used morphometric analyses to determine the efficacy of previously published characterizations to distinguish between the larvae of T. lacerata and T. onusta. Previous characterizations, especially those involving relative lengths of the caudal appendages, were generally found to be inadequate for distinguishing larvae of the two species. The most reliable characteristic for distinguishing the two species was found to be the length of the epiproct relative to the length of the paraprocts.
Landwer, Brett H. P and Sites, Robert W.
"Diagnostic Efficacy of Morphological Characters of Larval Tramea Lacerata Hagen and Tramea Onusta Hagen (Odonata: Libellulidae) in the Prairie Region of Missouri,"
The Great Lakes Entomologist: Vol. 38
, Article 9.
Available at: https://scholar.valpo.edu/tgle/vol38/iss2/9