Redescription of Ammodytoides gilli, the tropical eastern Pacific sand lance (Perciformes : Ammodytidae)

Ammodytoides gilli (Bean, 1895) is the correct name for the tropical easter n Pacific sand lance. Its range is extended from Cabo San Lucas, Baja Calif ornia south to Panama, Ecuador and the Galapagos Islands. Ammodytes lucasan us Beebe and Tee-Van, 1938 is a junior synonym. Types of both nominal speci es were re-examined. The species is redescribed based on 50 specimens (42.3 -115 mm SL) from 12 lots and is compared with other known species of Ammody toides. Changes in ontogeny from the smallest known specimen (42.3 mm SL, i llustrated) are detailed including reduction in the posterior dorsal fin lo be and development of branched dorsal and anal fin rays.