Early Evidence for Sexually Dimorphic, Ultraviolet Eyespots in Parnassius Smintheus, Doubleday, [1847]

Abstract

Ultraviolet (UV) reflective surfaces in butterflies have been documented across several groups and have been found to be related to both interand conspecific signaling (Silberglied & Taylor 1973, Papke et al. 2007). Most notably among butterflies, genera such as Bicyclus (Nymphalidae) and Colias (Pieridae) express ultraviolet reflectance which is used in communication (Silberglied & Taylor 1973, Robertson et al. 2005, Papke et al. 2007, Huq et al. 2019). Here, we present photographic, phenomenological evidence for UV reflective eyespots in Parnassius smintheus Doubleday, [1847] (Papilionidae), a high-elevation butterfly that is distributed throughout the Rocky Mountains and up into Canada as far north as Yukon Territory (Opler & Wright 1999). Figure 1 includes photographs of individuals from three P. smintheus subspecies, smintheus, magnus, and rubina, which all express UV reflectance on eyespots located on the ventral hindwing. Although this sample size is small, we note that these eyespots appear to be sexually dimorphic, with males having a single UV eyespot and females having either two or three UV eyespots. Our photo series was taken using a Nikon D7100 outfitted with a 60mm 1:4 UVVIS-IR lens and 60nm HBW/320-380nm blocked VIS/IR filter. We used Labsphere certified reflectance standards which are shown in each photograph. While the significance of this morphological finding is untested thus far, it may be related to signaling. The note presented here represents this preliminary finding, currently under further investigation. In Bicyclus anynana, UV reflective eyespots have been shown to have influence on mate choice by both males and females (Robertson et al. 2005, Huq et al. 2019). Alternatively, in P. smintheus, it may also be used as a way for the species to determine members of the same/opposite sex without respect to mate choice. This,