The number of ommatidia is abnormal in heterozygotes.
"Furrow stop" mutant. The eye discs contain 7-8 columns of ommatidial R cell clusters.
Progeny of da-/da- mothers show a more extreme B phenotype than the progeny of da+ mothers in triploid intersexes. SxlM1 reduces phenotypic expression of B in triploid intersexes.