Male Morphological Dimorphism in the Genji Firefly Nipponoluciola cruciata in Central Japan

The Japanese Genji firefly Nipponoluciola cruciata is famous for geographic variation in flash pattern. Such geographic variation has also been well studied in terms of ecology and molecular phylogeny. However, there are very few studies on geographic variation in morphology of this species. This study focused on morphological characteristics of males of this species in Yamanashi and Gunma Prefectures separated by the Kanto Mountains in central Japan. Previous studies have shown that this species in the two prefectures exhibits different genetic features as well as different flash patterns. This study aimed to explore morphological characteristics of males of this species and performed multivariate analysis using measurements previously published in the literature. As a result, allometric analysis between body length and elytra width suggested that this species exhibits different allometric patterns between the two prefectures. Moreover, cluster analysis of measurements of genitalia suggested that this species is completely separated into two different groups between the two prefectures. These results suggest the importance of further morphological studies to clarify the divergence of this species.