Abstract
Zulueta (1925) reported that four elytral pattern-types were inherited under the mode of “sex-limited inheritance” in the Spanish leaf-beetle, Phytodecta variabilis.
The Japanese species, P. rubripennis has no pattern (Fig. 1, A), but P. r. var. plagipennis has a considerable black stripe on each elytron (Fig. 1, B, C). So the writer has crossed between these two varieties with all combinations, to know the law of inheritance. The results obtained are listed in Table 1. From these data, it is no doubt that the stripe in P. r. var. plagipennis is due to a single autosomal dominant gene. Beside this fact, the variations of the elytral color and the width of the black pattern are discussed in this paper.
