Two Syntopic Batesian Mimics: Camponotus purius Santschi, 1929 Is a Distinct Species, Not a Morph of Camponotus lateralis (Olivier, 1792) (Hymenoptera: Formicidae)

The mimetic Mediterranean ant Camponotus lateralis (Olivier, 1792) has been considered to comprise two intraspecific morphs (here, morph 1 and morph 2), based mainly on differences in pilosity and morphometrics. The dimorphism hypothesis has so far been favored because 15% of previous samples were considered to originate from mixed colonies. We test whether the two morphs represent different species using morphometric data from 346 workers, single-nucleotide polymorphism (SNP) data from 103 individuals, and visual scrutiny of 2135 workers and 115 gynes from 138 nests for co-occurrence of both morphs within nests. Contrary to the previous assumption, our examinations suggest heterospecificity: morphometric nest-centroid clustering as well as SNP-based PCA and ADMIXTURE analyses separate morph 1 from morph 2. Only one nest contained both morphs, indicating that mixed colonies are rare and that most previous records likely resulted from sampling artefacts. We therefore recognize morph 2 as a separate species and redescribe it as Camponotus purius Santschi, 1929. The two species differ in morphology, SNP variation, and resemblance to Batesian Crematogaster models. Both establish colonies near Crematogaster and follow Crematogaster trails. The syntopic occurrence of Camponotus lateralis and C. purius is with 59% of localities unusually common for closely related ant species.