SPATIAL AND TEMPORAL PATTERNS IN CRYPTIC WING MORPHOLOGY IN THE AMERICAN SNOUT, LIBYTHEANA CARINENTA

Abstract

One of the most common butterflies in the United States is Libytheana carinenta (the American Snout). Despite being common, information about the species is limited in some respects. In a previous study of American Snout populations in southern Arizona, we found that the adult is polymorphic in its cryptic ventral hind wing pattern, with at least three different morphs termed variegated (found in both sexes), variegated-with-check (found in male only), and uniform (found in female only). In this study, I sought to examine the occurrence and relative frequency of these morphs across the butterfly’s North American range. To do this, I collected crowdsourced data on wing pattern, sex, date, and location from iNaturalist for the year 2022. I found that all three morphs occur throughout the butterfly’s range in space and time. I also recovered a strong male bias (66.5% males) in the data, consistent with a male bias found in our local sampling from the summer of 2022. Interestingly, the male bias depended on pattern, being more biased for the sexually dimorphic check/uniform forms than for the sexually monomorphic variegated form. Lastly, the variegated-with-check males were particularly strongly represented across eastern United States, relative to other parts of the range. The functional significance of variation in this wing pattern is unknown. An interesting future direction would be analysis of how the effectiveness of the various wing patterns in predator avoidance varies in the different parts of the butterfly’s range.