Serrula, a small comb-like structure on the ventral aspect of cheliceral movable finger in scorpions, has often been overlooked or ignored. Scorpion genera that are currently known to possess serrula belong to six families: Chactidae, Euscorpiidae, Iuridae, Pseudochactidae, Superstitioniidae, and Vaejovidae. All relevant literature on scorpion serrula is reviewed, and serrula of representative scorpion taxa is illustrated by SEM images. We suggest that the inconsistency in reporting serrula is based on several factors (or combination thereof): (a) serrula tines can quite often be broken off partially or completely, especially in adults; (b) serrula can be vestigial and hardly visible under a dissection microscope; and (c) serrula can be obscured by long, dense setae.
Graham, M. R., & Fet, V. 2006 . Serrula in retrospect: a historical look at scorpion literature (Scorpiones: Orthosterni). Euscorpius, No. 48: 1-19.