A new troglobitic species of the subfamily Pselaphinae (Coleoptera: Staphylinidae), Tychobythinus muxari n. sp., is described from Sicily (Ciavuli cave, Sant'Angelo Muxaro, Agrigento). Major diagnostic features are illustrated based on both male and female specimens. The new species shows some adaptations to cave life, i.e., pale brown color, setation consisting of long and flattened setae and suberect shorter setae, absence of wings, microphthalmia and elongated legs and antennae. It can be easily separated from the related taxa by the different shapes of the head and profemora and protibiae of the male, and of the aedeagus. The new synonymy Tychobythinus cameratensis (Karaman, 1959) = Tychobythinus gracilicornis (Raffray, 1914) (syn. nov.) is proposed. New data on morphology, taxonomy and/or distribution of T. andreinii (Dodero, 1919), T. controversus Poggi 1923, T. dentimanus (Reitter, 1884), T. foroiuliensis Pace, 1976, T. glabratus (Rye, 1870), T. gladiator gladiator (Reitter, 1885), T. majori (Holdhaus, 1905), T. mirandus (Dodero, 1919), T. myrmido (Reitter, 1882) and T. tibialis (Dodero, 1919) are provided.