Humidity-specialization
Guides
Darlingtonea kentuckensis
A troglobitic cave beetle endemic to eastern Kentucky karst systems. Adults measure 7.3–7.7 mm. The species exhibits surprisingly broad thermal tolerance (threshold ~20–24°C, mortality at 30°C within 24 hours), suggesting remnant physiological characteristics from epigean ancestors. However, it shows extreme specialization for constant high-humidity environments, with survival declining dramatically below 100% relative humidity and mortality within 3 days at 50–80% RH. Population densities can exceed 100 individuals per sand bank in suitable cave habitats.