The discovery of a new structure on the laterobasal aspect of the telson aculeus is described here for the first time. This structure, termed the laterobasal aculear serrations (LAS), is a row of minute denticles located on each side of the aculeus base, found exclusively in scorpion family Vaejovidae, thus potentially providing a new synapomorphy for this New World family. The LAS structure of major representative vaejovid genera and Vaejovis groups is illustrated with SEM micrographs. Also provided is a comprehensive list of non-vaejovid Recent scorpion genera examined where the LAS structure was found to be absent
