Larval stages and the megalopa of Pachycheles serratus are fully described and illustrated on the basis of laboratory-reared materials collected from Margarita Island, Venezuela. Complete development of P. serratus includes two zoeal stages and the megalopal (decapodid) stage, cultured at a water temperature of 25°C and salinity of 37‰. The first zoea lasts 5–6 days and the second lasts 8–10 days. A diagnostic character of the present species is the existence of a short mesial spine on the maxillular endopodite, unique among known zoeae of the genus Pachycheles. In addition, they can be distinguished from the first zoeae of P. laevidactylus and P. monilifer (western Atlantic congeners for which larval morphology is well-described) by size and ornamentation of the rostral spine, disposition of lateral spines on the abdominal somites, and setation of the maxilliped 3 in the second zoea. A comparative summary of zoeal morphology is provided for members of the genus Pachycheles.