A global phylogenetic analysis of trap‐jaw ants, Anochetus Mayr and Odontomachus Latreille (Hymenoptera: Formicidae: Ponerinae)

Abstract

We present a phylogeny of the trap‐jaw ant genera Anochetus and Odontomachus with dense taxon sampling representing all biogeographical regions and all species groups for both genera. Four nuclear protein‐coding genes (Long‐wavelength rhodopsin, Topoisomerase I, Wingless and Rudimentary) and one mitochondrial gene (cytochrome oxidase I) were sequenced for 221 individuals of Anochetus (44 species) and Odontomachus (38 species). Analyses using Bayesian and maximum‐likelihood criteria recovered essentially the same phylogenetic relationships, including strongly supported reciprocal monophyly of both genera. The analyses recovered nine of the 12 species groups previously proposed for Odontomachus and nine of the 22 species groups previously proposed for Anochetus. Based on these results, species groups are redefined. Anochetus contained an additional new, previously unrecognized group defined here as the hohenbergiae group. Divergence‐time analyses estimated the clade composed of Odontomachus + Anochetus arose during the early Paleocene, with Odontomachus and Anochetus diverging during the Eocene. Biogeographic analyses suggest that the most recent common ancestor (MRCA) of Odontomachus and Anochetus occupied either the Neotropical or Afrotropical region during the late Cretaceous and that the two genera radiated during the early Paleocene. The ancestor of Odontomachus originated in the Neotropical or Afrotropical regions, giving rise to lineages that radiated during the late Eocene, and the ancestor of Anochetus originated in the Neotropical region, giving rise to lineages that radiated during the early Eocene.

Phylogenetic Reconstruction of the Ancestral Chromosome Number of the Genera Anochetus Mayr, 1861 and Odontomachus Latreille, 1804 (Hymenoptera: Formicidae: Ponerinae)

“…First, there may be a trend for an increase in the chromosome number, mediated by an unbalanced fission-fusion ratio, at least in some animal taxa, especially ants (Imai et al, 1994(Imai et al, , 2001de Vos et al, 2020). Second, the karyotyped Anochetus species, belonging to six morphological groups well distributed along its phylogenetic tree (see Fernandes et al, 2021), tend to have a conserved number of n = 15. Moreover, early splitting karyotyped species of Odontomachus in the tree also have n = 15 (Figure 2).…”

“…Independent divergence-dating estimates show that the MRCA of Anochetus and Odontomachus would have arisen either in the Early Paleocene at about 64.8 Mya (Fernandes et al, 2021) or in the Early Eocene at about 52.5 Mya (Larabee et al, 2016). Biogeographical estimates, on the other hand, are still incongruous but leading toward the Neotropical region (Larabee et al, 2016;Fernandes et al, 2021). As increased taxon sampling leads to effective estimates of divergence time inference (reviewed by Bromham et al, 2018), Fernandes et al (2021) have an advantage.…”

“…Biogeographical estimates, on the other hand, are still incongruous but leading toward the Neotropical region (Larabee et al, 2016;Fernandes et al, 2021). As increased taxon sampling leads to effective estimates of divergence time inference (reviewed by Bromham et al, 2018), Fernandes et al (2021) have an advantage. According to these authors, Anochetus and Odontomachus appeared at around 53.9 and 51.4 Mya, respectively.…”

“…It is supported that Odontomachus arose in the Neotropical or Afrotropical regions, dispersing about 37 Mya in the Eocene. The Anochetus species shared an MRCA that probably originated in the Neotropical region and radiated about 58 Mya in the Paleocene, earlier than the estimated radiation of Odontomachus (Fernandes et al, 2021).…”

“…Among the Ponerinae, the genera Odontomachus and Anochetus extend out due to slightly chromosomal number inertia in the former compared to the later, and long sword-like mandibles that can open 180 • and close in a snapshot, being known as trap-jaw ants. Interestingly, these two genera are reciprocally monophyletic (Larabee et al, 2016;Fernandes et al, 2021). The most recent common ancestor (MRCA) of both genera probably emerged in the Neotropical or Afrotropical region at the late Cretaceous, about 65 Mya.…”