A new species of Charinus is described and illustrated from the Brazilian Atlantic Forest. Charinus ruschii sp. n. is found in Santa Lúcia reserve, Espírito Santo state, and is sympatric with C. brasilianus and C. montanus. The new species can be easily distinguished from the other species of the genus by the combination of the following characters: number of spines on the pedipalp tarsus, size and shape of the female genitalia, shape of the sternum and number of teeth in the cheliceral claw. The behavioral repertory is also described for this species based on five hours of qualitative and 24 hours of quantitative observations in order to define the behavioral categories. Five behavioral categories were detected and 21 behavioral acts. The most conspicuous category was Immobility, followed by Antenniform leg movement, Environmental exploration, Self-grooming, and Feeding. It was also found that juveniles spend longer time inside the shelter, even during peaks of adult activity, which could be related to a survival strategy.