Systematic revision of the neotropical ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae), with the description of thirteen new species

Abstract

This revision includes comparative morphological analysis, biological data from various sources and a consideration of geographical distributions. The genus is considered to be a natural group, including 31 valid species, of which 13 are here described as new. The species are distributed in four groups, morphologically and behaviorally characterized; individual keys and distributional maps are given. All types were examined, except for that of M. bituberculatus (Fabricius, 1798), probably lost; the species is considered inquirenda. M. duckei Forel, 1912 and M. leoninus var. nasutus Forel, 1912 are considered junior synonyms of respectively, M. balzani Emery, 1894 and M. staudingeri Emery, 1890. The Modes tus group comprises medium sized species that occupy or dig cavities under logs or rocks. Colonies may be large and may have one to several true queens. Workers forage in groups on the ground of tropical and subtropical forests, recruiting nestmates toward large food items. In the Modestus group are described as new M. ayri, M. caete and M. cupecuara. The Leoninus group comprises larger species, the gamergates of which take over the reproductive function. Nests occupy cavities under logs, with no traces of architecture. Workers forage individually on the ground or on shrubs, tending membracid nymphs. New species in this group are M. acauna, M. cyendyra, M. pacova and M. timbira. Species of the Silvestrii group maintain apparent non-obligatory lestobiotic relations with several genera of Attini. They occupy secondary cavities of the nests of their fungus-growing hosts and always have monogynous colonies with true queens. New in this group are M. cuatiara, M. mondabora, M. piriana, M. poatan and M. tasyba. The Pusillus group includes the smallest species of the genus, which live in general in diffuse colonies in the litter of tropical and subtropical forests. Some species may have colonies either with gamergates or with true queens. The shape of the mandibles and the relatively large eyes suggest predatory habits. M. miri is the only new species in the group. Lectotypes and paralectotypes are designated for M. balzani, M. foreli, M. goeldii, M. iheringi, M. latreillei, M. leoninus, M. modestus, M. myops, M. pusillus and M. symmetochus.