Differences in Troglomorphism and Sexual Dimorphism in Two Sympatric Subtroglophile Crickets of Genus Troglophilus (Insecta: Orthoptera)

ABSTRACT We investigated morphological variation and sexual dimorphism in two species of syntopic cave crickets (Troglophilus neglectus and T. cavicola) from Northern Balkans. T. cavicola is able to penetrate deeper in caves and stays there for longer periods than T. neglectus. Yet, it has not exhibited clearly stronger constructive (body size, elongation of appendages, increased spinulation) or reductive (eye reduction) traits than T. neglectus. Moreover, contrary to expectation, there is no clear association between more prolonged staying in a stable cave environment and overall lower morphological variability in T. cavicola. Only some of its morphological traits actually showed less while other showed more variation than in T. neglectus. While T. cavicola males are larger than females, there is no such difference in T. neglectus. This may help males of T. cavicola being more competitive towards overall larger T. neglectus. With the exception of the body size, overall sexual dimorphism was better expressed in larger T. neglectus. The morphospaces occupied by males and females overlap more strongly in T. cavicola than in T. neglectus, indicating that ecological niches of both sexes are better separated in the latter species.