Calastacus laurentae n. sp. is the second species of Calastacus from France and Europe besides C. laevis de Saint Laurent, 1972. The description is based on two small specimens collected on the continental slope of the Bay of Biscay, off Brittany (France). The holotype is nearly complete while the second specimen is much damaged with a missing carapace; it is not considered a paratype. Calastacus laurentae n. sp. differs from all known Calastacus species by having a pair of large distal spines on the rostrum and spinules on lateral borders of the telson. It can be distinguished from C. laevis by the pereopod 1 bearing a small subdistal spine on both the upper and lower borders of the merus along with a fine longitudinal upper carina on the propodus; by contrast in C. laevis, there are one large upper spine and five large lower spines on the pereopod 1 merus and no upper carina on the propodus. Also in the new species, the terminal suture on the uropodal exopod is faint and unarmed while it is well defined and bears spinules in C. laevis.
Crustacea, Decapoda, Axiidae, Calastacus laurentae n. sp., France, new species.