A new ghost shrimp of the genus Lepidopthalamus from the Pacific coast of Colombia (Decapoda: Thalassinidea: Callianassidae)

Lepidophthalmus rafai is described from an intertidal shoreline in the vicinity of Buenaventura, Pacific coast of Colombia, South America. While recent collecting has uncovered populations assignable to described and undescribed species of the genus in intertidal habitats of the tropical eastern Pacific, most of these are forms with a ventrally plated or armed abdomen and a strongly trilobate posterior margin on the telson, features that suggest close relationship to L. bocourti (A. Milne Edwards) or L. eiseni Holmes. The new species is smaller in size than its congeners and is the most southerly distributed species of the genus known from the eastern Pacific. It lacks conspicuous sclerotized plates on ventral surfaces of the abdomen, a feature that it shares with a pair of antitropically distributed species in the western Atlantic. The two Atlantic forms, and the herein described new Pacific species, may have diverged from common stock partitioned by closing of the Panamanian Isthmus. The occurrence of L. rafai in a perturbated, hypoxic estuarine habitat is consistent with tolerances and adaptations documented previously for other species of the genus.