Phylogenetics of the new world honey ants (genus Myrmecocystus) estimated from mitochondrial DNA sequences

Abstract

Honey pot workers that store immense amounts of food in the crop and are nearly immobilized due to their highly expanded gasters are known from a variety of ant species in different parts of the world, presumably as adaptations to regular food scarcity in arid habitats (H€ olldobler and Wilson, 1990). Although these so called repletes are taxonomically fairly widespread, the phenomenon is most commonly associated with species of the New World honey ant genus Myrmecocystus, whose repletes have a long lasting reputation as a delicacy with indigenous people. As repletism supposedly occurs within all species of Myrmecocystus, it seems plausible that this key innovation promoted the diversification of honey ants after formation of the North American deserts. Accordingly, the distribution of the genus is centered in arid parts of southwestern North America, including the Mohave, Sonoran, Great Basin, and Chihuahuan Deserts. The genus Myrmecocystus seems to be most closely related to Lasius (Snelling, 1976), and Bolton (1994) placed Myrmecocystus and the genera Acanthomyops, Euprenolepis, Lasius, Paratrechina, Prenolepis, Protrechina, Pseudolasius, and Teratomyrmex in the same tribe Lasiini. Myrmecocystus can be distinguished from all Nearctic genera of Formicinae by the elongatedmaxillary palpi, of which the fourth segment is as long as, or longer than, the combined lengths of the two following segments. Snelling (1976) subdivided the genus into three subgenera: Myrmecocystus, Eremnocystus, and Endiodioc-