Abstract
On the 17 extant subfamilies of ants, Dolichoderinae is one of the four major species-rich clades (with Formicinae, Ponerinae, and Myrmicinae), and a cosmopolitan group including some of the world’s most invasive species such as the Argentine ant and white-footed ant. It comprises currently 846 species in 28 extant and 20 extinct genera (Bolton, 2019). Most of the fossils are Cenozoic in age, which accords with the timeline of the Dolichoderinae as proposed by molecular phylogenetic studies (Ward et al., 2010; Moreau & Bell, 2013; Borowiec et al., 2019). According to these studies, crown-group dolichoderines arose sometime between 66 and 53 million years ago. Thus, around or after the Cretaceous–Paleogene transition, although this would have been preceded by approximately 30 million years of stem group evolution. Cretaceous dolichoderines are exceedingly rare indeed, and the only two known genera—Eotapinoma Dlussky, and Chronomyrmex McKellar, Glasier & Engel, from Canadian Campanian amber (79–78 Ma)—although originally placed in the Tapinomini and Leptomyrmecini, respectively, have been suggested to be stem dolichoderines (Dlussky, 1999; McKellar et al., 2013; Boudinot et al., 2016). Another fossil dolichoderine was reported from “Cretaceous amber” of Ethiopia (LaPolla et al., 2013: suppl. fig. 5) but this amber is now known to be much younger in age, likely Miocene (Perrichot et al., 2016, 2018). The first definitive crown-group dolichoderines are thus currently from the middle Eocene (50–45 Ma) of Europe and North America, belonging to various extinct species of the genera Dolichoderus, Iridomyrmex, Liometopum, and Tapinoma (see Barden, 2017). Some earlier crown-group dolichoderines may be present in early Eocene (55–52 Ma) ambers from France, India, and China (Perrichot, pers. observ.), but these have yet to be formally described.