Polytene chromosomes normal.
Heterozygotes have a reduced number of sex comb teeth on the first tarsal segment of the prothoracic leg in males. Homozygotes show failure of head involution. Labial to maxillary transformation in the adult head and prothoracic to mesothoracic transformation in the adult thorax.
There is a slight penetrance and expressivity of the 'Scx' phenotype: extra sex combs are seen on the meso- and metathoracic legs.
Revertant.