Amino acid replacement: S554F.
Nucleotide substitution: C1661T.
Adults carrying fz25B2.Act5C in a fz21 background have an average of 2.3 +/- 0.7 extra tarsal joints in the leg compared to wild type.
fz25B2.Act5C shows poor rescue of the wing margin phenotype of fz21 fz2C1 double homozygous clones.