Escapers of lethality show a disorganized eye phenotype. Majority of ommatidia have extra R7 cells, generated by transformation of cone cells. Some of the extra photoreceptors resemble outer (R1-R6) photoreceptor neurons. Mystery cells assume R3/R4 fates. In heterozygous condition, 1-7% of ommatidia show an extra R7 cell or an occasional gain or loss of an outer photoreceptor cell. In embryos, 37% of hemisegments show an extra chordotonal organ in the lateral cluster. In clones in the eye the ommatidial phenotype changes abruptly at the boundary, indicating that the mutant phenotype is cell autonomous. There is no absolute requirement for sty+ in any of the photoreceptor neurons, and sty+ can function non-autonomously to prevent cone cells from differentiating as R7 photoreceptor neurons. The requirement for sty+ function is mainly cell autonomous in the cells that differentiate as extra R7 cells.
Pupal lethal when hemizygous. The number of tracheal branches emanating from the dorsal and ganglionic branches is higher than normal in homozygous embryos.