A multi-method approach to investigating the subspecific designation of the Euschistus servus species complex

Euschistus servus (Say) (Heteroptera: Pentatomidae) is distributed throughout North America and is currently subdivided into two subspecies E. s. servus (Say, 1831), found in the southern U.S., and E. s. euschistoides (Vollenhaven, 1861) in the northern U.S. An intergrade (anatomically intermediate of both subspecies) population inhabits the central U.S. from Maryland to Kansas. This study seeks to reevaluate the subspecific designations established by Say and Vollenhoven and determine whether E. servus subspecies and intergrade populations express distinct suites of taxonomically important morphological characteristics throughout the U.S., or if the characteristics exhibit clinal variation. We will quantify geometric morphometric data (i.e., relative lengths of the juga and tylus) from specimens collected along a north-south gradient and use a principal component analysis (PCA) to determine if there is a significant difference within the subspecies morphology. Our results may provide the basis for challenging the current subspecific designation of E. s. servus and E. s. euschistoides. If our PCA determines our measured morphological characteristics are not significantly different, we will dispute the subspecific designation.  Likewise, if we find that these characteristics are subject to clinal variation, we will dispute the subspecific designation.  This research will help inform further taxonomic designations and standardize subspecific designations.