Phenotype images of Gryllus personatus and five resulting morphological measurements

<p class="MsoNormal">Sexual size dimorphism (SSD) and sexual shape dimorphism (SShD) are of interest to evolutionary ecology, but the two phenomena can very easily be conflated by not taking a multivariate approach to measuring size. In our study we draw attention to this problem by measuring four body size dimensions (maxillae span, head width, pronotum length and mean hind femur length) in lab-reared individuals of the badlands cricket (Orthoptera, Gryllinae, <em>Gryllus personatus</em>) and conducting a variety of multivariate analyses to test whether there is SSD and/or SShD.</p> <p class="MsoNormal">We found that males had wider heads and maxillae than females, and females had longer pronota and hind femora than males. This difference in the direction of sexual dimorphism indicates SShD. However, multivariate methods failed to detect SSD, instead confirming that the sexes primarily differ in body shape. We suggest that orthopterists studying sexual dimorphism minimally measure head width, pronotum length and hind femur length as a standard that will allow a more repeatable and generalizable assessment of the prevalence and direction of both SSD and SShD.</p>