Phylogenetic Analysis of the North American Beetle Genus Trichiotinus (Coleoptera: Scarabaeidae: Trichiinae)

Abstract

A hypothesized evolutionary history of the North American endemic trichiine scarab genus Trichiotinus is presented including all eight species and three outgroup taxa. Data from nineteen morphological traits and CO1 and 28S gene sequences were used to construct phylogenies using both parsimony and Bayesian algorithms. All results show that Trichiotinus is monophyletic. The best supported topology shows that the basal species T. lunulatus is sister to the remaining taxa that form two clades, with four and three species each. The distribution of one lineage is relatively northern while the other is generally more southern. The ancestral Trichiotinus lineage arose from 23.8-14.9 mya, and east-west geographic partitioning of ancestral populations likely resulted in cladogenesis and new species creation, beginning as early as 10.6-6.2 mya and as recently as 1.2-0.7 mya. Morphological character evolution is also briefly discussed. The limited distribution of T. rufobrunneus in Florida and T. viridans in the Midwest mainly due to urban development and widespread agriculture makes these two species of conservation concern.