Beetles, barcodes, and big data: a deep dive into the phylogeny of Harpalinae (Carabidae)

The ground beetles (Carabidae) are a highly species-rich lineage of the
Coleoptera, with over half of their diversity concentrated in the ~20,000
described species in the subfamily Harpalinae sensu lato. As a presumed
recent radiation lacking deeply distinct morphological divisions, their
taxonomic classification has been challenging, while molecular studies
remain limited in the number of genes and taxa sampled. Using ~450
mitochondrial genome sequences from across the Carabidae and the major
biogeographic realms we investigate the tribal relationships in
Harpalinae. Our phylogenetic analysis supports a revised system that
broadly divides the harpalines into two major reciprocally monophyletic
lineages, corresponding to a narrowly defined Harpalinae sensu novo and a
distinct Lebiinae. Within Harpalinae, we recover well-supported subclades
that mostly represent existing tribes (e.g., Harpalini, Pterostichini,
Licinini, Platynini), while clades in Lebiinae required the recognition of
three new or redefined clades: Lebiini, Agrini, and Odacanthini. We also
establish the polyphyletic status of the ‘Truncatipennes’ defined by
truncated elytra and traditionally encompassing most ‘lebiomorphs’, which
are split into the Lebiinae and at least two additional lineages,
corresponding to the Dryptinae and Brachininae (bombardier beetles)
branching below the Harpalinae + Lebiinae clade. The mitogenome data were
extended to include ~7000 species of Carabidae by adding all available
cytochrome c oxidase subunit I (COI) barcodes and other legacy sequences.
The resulting phylogeny broadly concurs with the tribal boundaries defined
by mitogenomes and provides a curated barcode reference library for
species identification. The unprecedented scale of mitogenome sequencing,
combined with dense taxon sampling of barcodes, resolves a particularly
complex portion of the beetle tree-of-life.