First record of Macrobrachium grandimanus (Crustacea, Decapoda, Palaemonidae) from Guam, Micronesia

Abstract

The Hawaiian river shrimp Macrobrachium grandimanus (Randall, 1840) is an amphidromous brackish water prawn that inhabits the Hawaiian Islands (type locality), Ryukyu Islands, Melanesia (Fiji, New Caledonia), and Polynesia (Tonga). Here, we report a new record of this species from Guam, Micronesia. Two genetically and morphologically differentiated lineages of this species are known: the Hawaiian and the Ryukyu lineages. Morphological and mitochondrial DNA analyses revealed that the Guam population is closely related to the Ryukyu lineage.