Molecular phylogenetics provides insights into biogeography and character evolution in the assassin bug tribe Saicini (Hemiptera: Reduviidae: Emesinae)

Reduviidae (assassin bugs) are a species-rich group of terrestrial predatory insects, exhibiting remarkable diversity in foreleg morphology. The tribe Saicini (Hemiptera: Reduviidae: Emesinae) displays various morphological modifications of the foreleg. Although the definition and classification of Saicini have undergone considerable changes in recent years, the higher-level phylogeny and evolutionary history of the tribe remain poorly understood. Here, we generated a molecular dataset for Saicini to investigate its phylogeny, historical biogeography and foreleg character evolution. Our phylogenetic results corroborate the monophyly of Saicini and its two subtribes, Saicina and Tagalina, and reveal two new genera: Montopolytoxus gen. n. and Webbisaica gen. n. Molecular dating and biogeographic analyses suggest that the crown group of Saicini originated in the Late Cretaceous (ca. 72.05 Ma), followed by multiple transcontinental dispersal events that shaped the current tropicopolitan distribution of the tribe. Ancestral state reconstruction of six foreleg characters indicates that the ancestral Saicini possessed a moderately elongate procoxa, a curved protibia and a short protarsomere I. The presence of tuberculate setae on the foreleg is inferred to be the ancestral condition for Tagalina.