WORKER POLYMORPHISM IN THE RED-HEAD BULLDOG ANT (HYMENOPTERA, FORMICIDAE), WITH DESCRIPTION OF NEST STRUCTURE AND COLONY COMPOSITION

Five nests of Myrmecia froggatti were dug out in the dry Eucalyptus woodland around Mt. Gournet, Queensland, northern Australia. Nest structure was simple; a single, vertical unbranched shaft that connected 6-12 chambers down to 80-145 cm. Colonies were monogynous and of small size; each contained one ergatoid queen, an average of 38 workers, and several brood. Ergatoid queens had a sperm-filled spermatheca and between 15-18 ovarioles, whereas workers had an empty spermatheca and 4-15 ovarioles. Pronotum width and head width of workers showed isometric growth. However, allometric growth was observed between the width of the pronotum and the width of the fourth segment of the abdomen. Number of ovarioles was positively correlated with the abdomen width. Thus, large sized workers had a disproportionally larger number of ovarioles than smaller sized workers. The function of large workers of M. froggatti is discussed.