A new species, Macroperipatus valerioi Morera-Brenes & León, is described from Río Damitas, 16 Km north of Puerto Quepos (9°34' N, 84°10' W), Costa Rica. The inner jaw bears 2 accessory teeth, the first more developed and with 13 denticles. Outer jaw with only one accessory tooth. Fourth creeping pad of fourth and fifth lobopods is slender and curves itself around the nephridial tubercle, which remains free and directed towards the right side of the third and fourth pads. Fourth pad complete or broken in a single individual. Uniform dorsal color brown in life. This species appears to be closely related to Macroperipatus geagi (Bouvier) from South America.