Emeryia, Xenometra, zoserka: it's a boy, again! The misleading morphology of Cardiocondyla male ants

Abstract

Wingless “ergatoid” males of the ant genus Cardiocondyla have repeatedly been described as females of novel genera of workerless social parasites (Emeryia and Xenometra), which after recognition of their real nature were synonymized with Cardiocondyla. Examination of ants newly collected from Comoé National Park in Côte d’Ivoire, West Africa revealed that winged Cardiocondyla males have sparked a similar misidentification: the “winged female sexuals” of the supposed inquiline Cardiocondyla zoserka Bolton 1982, known only from the type material from Nigeria, are in fact the winged males of their presumed host, a species of the Cardiocondyla shuckardi group (sensu Seifert 2002). The types of C. zoserka are immediately recognizable by their strangely modified antennal funiculi with cup-shaped apical segments, which do not resemble any other known ant antenna. More than twenty winged individuals from two Cardiocondyla colonies from the flood plain of Comoé River exhibited the same strange modifications of their antennae and were otherwise also similar to the C. zoserka type specimens. However, these winged ants turned out to be winged males rather than winged female sexuals. The inspection of the holotype and one paratype of C. zoserka verified that they also were males: like the winged males from Comoé N.P., they have concealed male genitals and ocelli, which are considerably larger than those of the female sexuals of Cardiocondyla. All female sexuals and workers found in the colonies with the bizarre winged males from Comoé N.P. had antennae with a three-segmented club as is typical for this genus. Sequences of the mitochondrial cytochrome c oxidase subunits I (CO I) and II (CO II) of a winged male and two nestmate workers showed that they are close to C. venustula and C. shuckardi but differ from them in about 10% of the base pairs. Other samples of Cardiocondyla collected in Comoé N.P. belong to C. venustula and related species. Their males were always ergatoid or “intermorphic” (i.e., ergatoid with rudimentary wings), as previously found in other populations of C. venustula, and never winged with modified antennae.