Investigating the phylogenetic placement of ectoparasitic families Cyclotornidae and Epipyropidae: Multigene insights into Zygaenoidea systematics (Lepidoptera)

Zygaenoidea is a highly diverse lepidopteran superfamily whose monophyly remains unresolved, particularly regarding the phylogenetic positions of the two ectoparasitic families, Cyclotornidae and Epipyropidae. In this study, multi-gene datasets comprising 22 genes (13 mitochondrial protein-coding genes (PCGs), 2 mitochondrial rRNA genes, and 7 nuclear PCG fragments) were assembled from 62 representative samples covering all 11 recognized zygaenoid families and all 29 ditrysian superfamilies. Maximum likelihood and Bayesian inference methods were used to reconstruct phylogenetic relationships. Our results consistently showed that the traditionally defined Zygaenoidea was non-monophyletic. Cyclotornidae and Epipyropidae were recovered together in most of our analyses, often with moderate to strong support, and were placed near the base of Apoditrysia, distantly from the core Zygaenoidea, possibly as sister to Douglasioidea. However, given the long branches leading to these two lineages, this sister-group relationship should be interpreted with caution pending further evidence. In contrast, the remaining nine families constituted a well-supported monophyletic group (core Zygaenoidea). Based on these findings, we propose that Zygaenoidea sensu stricto should include only the nine core families and exclude Cyclotornidae and Epipyropidae. This study provides a robust phylogenetic framework for Zygaenoidea and offers new insights into the higher-level systematics of Ditrysia.