Mate Competition

Male Competition in Cardiocondyla
The following summary is from Heinze et al. (2004):

Ergatoid males have as yet been found in all Cardiocondyla species, from which males are known (Kugler, 1983; Heinze, 1999; Seifert, 2003). However, ergatoid males of Cardiocondyla obscurior and a few related species (e. g., Cardiocondyla wroughtonii, Seifert, 2003) are atypical in that they have elongated mandibles and regularly attack also adult rivals. In other species, such as Cardiocondyla mauritanica, Cardiocondyla emeryi, Cardiocondyla kagutsuchi, and Cardiocondyla minutior, fighting appears to be less common among adult males, and ergatoid males use their strong mandibles predominantly to crush the soft cuticle of freshly eclosed ergatoids (Heinze et al., 1993, 1998; but see Yamauchi and Kinomura, 1993 for regular adult male fighting in C. minutior from Okinawa). Because some callow males occasionally remain undetected, several adult males may co-occur especially in large colonies of these species (Heinze et ai., 1998; Anderson et ai., 2003). Furthermore, C. obscurior and C. wroughtonii nest in ephemeral cavities in plant material, such as coiled leafs of lemon trees or aborted coconuts, whereas colonies of the other species inhabit holes in the ground.