Tusked Males, Male Dimorphism and Nesting Behavior in a Subsocial Afrotropical Wasp, Synagris cornuta, and Weapons and Dimorphism in the Genus (Hymenoptera: Vespidae: Eumeninae)

Abstract

Abstract Synagris wasps (Hymenoptera: Vespidae: Eumeninae) include some of the most spectacular examples of exaggerated secondary sexual “weapons” known. I examined the scaling relationship between tusk length and head width in S. cornuta, a widely distributed, Afrotropical species. Data from museum collections and field observations demonstrate that, unlike most aculeate Hymenoptera, males of S. cornuta are larger, on average, than females and are dimorphic for mandibular tusk length with a discontinuous scaling relationship shape for head width. Other measures of body size are also examined. I also studied female nesting behavior and male behavior in the field in Cote d'Ivoire, West Africa. Nests and nest construction and other female behaviors are described. Most nests were constructed on the undersides of leaves of Aframomum latifolium Afz. (Zingiberaceae) using soil from termite tunnels or old S. cornuta nests moistened with water from leaves. As reported by previous authors, females progressively pr...