Abstract

The genus Leocrates is currently made up of 11 nominal species, of which Leocrates chinensis Kinberg, 1866 is the type species. Kinberg's original description is brief, and the diagnostic morphological characters are poorly defined. Therefore, numerous subsequent records in different world regions have been considered doubtful. Numerous specimens of Leocrates collected by SCUBA diving in various locations of Robinson Crusoe Island (33 degrees 37'S, 78 degrees 51'W) in the Juan Fernandez Archipelago, between 4 and 10 m depth were examined and determined as a new species herein named Leocrates ernstehlersi n. sp. It is characterized by the size of anterior and posterior eyes, the median chaetigers with scarce notochaetae and neurochaetae per bundle; neurochaetal blades are 4-14 times longer than wide and neuracicular lobes slightly longer than wide. A key to identifying species of Leocrates having large anterior eyes and anterior eyes/prostomial width ratio between 1/4 to 1/8 is also included.