An amphidromic prawn, Macrobrachium latimanus (von Martens, 1868) (Decapoda: Palaemonidae), discovered on Pitcairn, a remote island in the southeastern Pacific Ocean

Abstract

The discovery of a population of Macrobrachium latimanus (von Martens, 1868) in a small pool on Pitcairn Island is a remarkable find, largely due to the island's isolation, the apparent small size of the prawn's population, and the paucity of suitable freshwater habitat. As in many southeastern Pacific islands, the volcanic origin of Pitcairn Island by geological activity at 'hot spots' through a pre-existing ocean floor, requires that their original colonization by the prawn must have resulted from long-distance dispersal. Like most carideans that live in freshwater and have small-size eggs, M. latimanus is an amphidromous species whose larvae are planktonic and must develop in a saline environment in estuaries and the open sea. After a period of some months in the marine environment, passing through many larval stages, the juveniles migrate upstream to the adult freshwater habitat. Macrobrachium latimanus has a widespread distribution throughout the Indo-West Pacific with Pitcairn Island, at 25°04'S, 130°06'W, now appearing to mark a new record for the southernmost and easternmost extent of its distribution.