A new species of crayfish, Procambarus (Austrocambarus) maya, is described from a salt marsh in the Sian Ka'an Nature Reserve, Quintana Roo, Mexico. The new species is most similar morphologically to Procambarus (A.) llamasi Villalobos, 1954, from which it can be distinguished by the absence of pubescence on the chelae; a gonopod with a large, mesially concave, blade-like mesial process, and a central projection and cephalic process basally fused. Other differences that separate the new species from P. llamasi are: the chelae are more slender, with the dactyli being longer than the palms; a pentagonal epistome, not heptagonal; a longer and more acute acumen; lateral spines of the rostrum and distolateral spine of the antennal scale more acute; antennal angle of the carapace with a well developed spine instead of a small projection; two spines on the pterygostomian angle of the carapace instead of three or four; and a narrower areola in which the suprabranchial grooves converge dorsally in less than half the length of the areola. The annulus ventralis of the new species is oval-shaped, the preannular plate has a straight anterior margin and is not completely covered laterally by the anterior sternal plates.