Data from: Levels of sex steroids in plethodontid salamanders: A comparative study within the genus Aneides

Derived monomorphism is a condition in which males and females are
phenotypically similar, but the similarity is derived.  Derived
monomorphism typically evolves from sexual dimorphism or from a different
monomorphic state.  We examined the hormonal basis of derived
monomorphism in the salamander genus Aneides (Plethodontidae).
 We reject our hypothesis that circulating levels of androgens
explain the derived traits, such as enlarged jaw musculature, in females
(some would call them “male-like traits”).  There was no clear
pattern of differences in androgen levels or degree of dimorphism in
androgen levels, between the sexually dimorphic Aneides hardii and the
other, derived monomorphic, species studied.  Concentrations of
testosterone and dihydrotestosterone were higher in males than in females
in all species examined. The degree of sexual dimorphism in androgen level
was also consistent among the species studied. Levels of androgens in
female plethodontids have not been previously reported.