Platorchestia platensis (Kroyer, 1845)

Myers, Alan A. & Lowry, James K., 2023, The Beach-hopper Genus Platorchestia (Crustacea: Amphipoda: Talitridae) on Atlantic Ocean Coasts and on those of Associated Seas, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 485-505 : 503

The enigmatic Platorchestia platensis

Atlantic species of Platorchestia , with one exception, are endemic to clearly defined single continuous regions ( Fig. 14 ). It is remarkable, then, that P. platensis ( Krøyer, 1845) is now known to occur in two widely separated localities, the northeastern Atlantic on the one hand, where it is widespread, and the southwestern Atlantic on the other, where it is currently known from a single collection only in the La Plata river in Uruguay (the type locality). It is tempting to assume that the Uruguay population has been introduced from Europe, since Montevideo has been an important commercial destination for European ships for centuries. Whether upper shore wrack inhabiting talitrids could be, or have been in the past, transported through ship’s ballast as suggested by Mead et al. (2011), is difficult to determine. Unfortunately, little collecting of beach amphipods has been reported from Uruguay or Argentina. If P. platensis is found to be of wide occurrence along Uruguayan and Argentinian coasts, then introduction may not be the most plausible explanation. If, on the other hand, no other records are forthcoming, then introduction from Europe may be the most parsimonious explanation.

Figures

Figure 14. Distribution of Platorchestia in the Atlantic Ocean and associated seas.