Metathorax developed more than any other bx allele and strongly bristled. Halteres directed ventrally, large, flat, and winglike with veins and bristles. Mesothorax shows clear stripe or bifida condition. Wings usually spread, often dragging. Sternopleural and tibial and ventral bristles of third leg resemble those of normal second leg. Ubxbx-W/bxd wild-type. Viability and fertility fair. RK2.
Hollander, 1934.
Arose in: Same female as Ubx1.
Stated to be lost.