Rediscovery of the Rare Pilumnid Crab, Actumnus Simplex Rathbun, 1911 (Decapoda, Brachyura) and a New Record for the Persian Gulf

AbstractActumnus simplex Rathbun, 1911, described 100 years ago and never reported again since, is recorded for the first time from the Persian Gulf. The species is characterized by a prominently convex dorsal carapace surface, regions that are weakly defined, four serrated anterolateral teeth, and a gently serrated frontal margin with a distinct median notch. It is morphologically close to Neoactumnus convexus Sakai, 1965, and N. unispina Garth & Kim, 1983, both from the western Pacific, but is easily distinguishable by possessing a distinct median notch in the frontal margin.