“Antennapetlia”: An Unusual Antennal Mutation in Tribolium castaneum1

Abstract

There have been three previously reported antennal mutations for Tribolium castaneum (Herbst) (“paddle,” Park and Frank 1951; “fused antennal segments,” Sokoloff 1960; and “short antennae,” Krause et al. 1962). In each of the above cases the mutation merely involved a reduction in the number of antennal segments due either to complete loss or fusion of certain segments. “Antennapedia,” ap, which apparently arose as a spontaneous mutation in a laboratory stock of T. castaneum, exhibits, in addition to the reduction and fusion of antennal segments, the presence of tarsal segments and the two tarsal claws on the antenna to give a “leglike” appearance. In its less extreme expression only partial fusion of the ninth and tenth distal segments of the antenna is evident, but the mutant is easily distinguished by the tarsal claws arising from the eleventh antennal segment. Genetic evidence from F1, F2, and backcross data (cf. table 1) indicates that this mutation is inherited as an autosomal recessive. Although phenotypic expression is varied, the mutation exhibits complete penetrance and its expression does not overlap with that of the normal wild type antenna. The camera lucida drawings of figure 1 illustrate the contrast which exists between the antenna of wild type with that of “antennapedia.”