Grappling with homoplasy: taxonomic refinements and reassignments in the ant genera Camponotus and Colobopsis (Hymenoptera: Formicidae)

Abstract

Camponotus and Colobopsis are widely distributed and species-rich genera in the ant tribe Camponotini. Molecular phylogenetic studies demonstrate that they are not sister taxa, but several lineages within each genus have converged to a remarkable degree, confounding the taxonomy of these ants. Based on multiple lines of evidence, including worker and male morphology, we demonstrate that: (1) three species of “Camponotus” belonging to the subgenus Myrmotemnus, including its type species, are in fact members of the genus Colobopsis; (2) four species previously assigned to Colobopsis belong to the subgenus Myrmamblys of Camponotus; and (3) three Nearctic taxa recently placed in Colobopsis are members of the genus Camponotus and closely related to Camponotus clarithorax. These taxonomic findings yield the following new or revived combinations: Colobopsis moeschi (comb. nov.), Colobopsis moeschi lygaea (comb. nov.), Colobopsis nutans (comb. nov.), Colobopsis nutans cleliae (comb. nov.), and Colobopsis reichenspergeri (comb. nov.); Camponotus apostemata (comb. nov.), Camponotus aurelianus (comb. rev.), Camponotus cavibregma (comb. nov.), Camponotus horrens (comb. rev.), Camponotus politae (comb. rev.), Camponotus trajanus (comb. rev.), and Camponotus yogi (comb. rev.). A further consequence is the following generic synonymy (senior synonym listed first): Colobopsis = Myrmotemnus syn. nov., and Camponotus = Dolophra syn. rev. At the species level, we argue that Camponotus apostemata and Camponotus cavibregma are junior synonyms (syn. nov.) of Camponotus yogi, and Camponotus quercicola is a junior synonym (syn. nov.) of Ca. laevigatus. Taxonomic comments are also provided on some members of the Camponotus reticulatus group, with Camponotus adustus (stat. nov.) and Ca. leucodiscus (stat. rev.) being recognized as distinct species rather than subspecies of Ca. bellus. A male-based diagnosis of the Camponotini is provided, and differences between the males of Colobopsis and Camponotus are documented and illustrated for the first time. This study reveals new character systems of potential value to the systematics of these ants, including features of the male genitalia, and emphasizes the value of reciprocal illumination between phylogenomics and critical morphological analysis.