FEMALE DIMORPHISM IN A SOCIAL HALICTINE BEE, HALICTUS (SELADONIA) AERARIUS(SMITH)(HYMENOPTERA, APOIDEA)

抄録

There are two types of females in a social halictine bee, Halictus(Seladonia)aerarius(SMITH). One is large and macrocephalic with dark-coloured mandibles, labrum, legs and metasomal sterna, while the other, which involves the majority of the specimens examined, shows the opposite tendencies in the characters concerned. The two types are distinct from each other in the extremes, although connected by intermediate individuals. Seemingly, this morphological differentiation corresponds to the functional differention of the queen(macrocephalic)and worker(microcephalic). But it was observed that a microcephalic female can occasionally found a nest independently, suggesting a slight discrepancy between morphological and functional differentiation;nevertheless the former attains the highest level of the caste differentiation among the social halictine bees so far studied. As another Japanese species of the same subgenus, H. (S.)tumulorum LINN'E has a simple, solitary life history, the subgenus Seladonia offers a further instance to the co-existence of both solitary and social species within one subgenus;such instances are frequent among halictine bees.